GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill and Intangible Assets by Operating Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Apr. 01, 2025	Dec. 31, 2024
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,726,386		$ 1,214,053
Intangible Assets	333,236		84,563
American National
Finite-Lived Intangible Assets [Line Items]
Goodwill			288,842
Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Goodwill	512,333	$ 512,333
Wholesale Banking \| Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Goodwill	399,600
Consumer Banking \| Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Goodwill	112,700
Operating segments \| Wholesale Banking
Finite-Lived Intangible Assets [Line Items]
Goodwill	1,249,654		850,035
Intangible Assets	52,037		8,714
Operating segments \| Wholesale Banking \| Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Goodwill	399,600
Intangible Assets	46,300
Operating segments \| Consumer Banking
Finite-Lived Intangible Assets [Line Items]
Goodwill	476,732		364,018
Intangible Assets	657		778
Operating segments \| Consumer Banking \| Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Goodwill	112,700
Corporate Other
Finite-Lived Intangible Assets [Line Items]
Goodwill	0		0
Intangible Assets	280,542		$ 75,071
Corporate Other \| Sandy Spring
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 244,400

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 18: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 19: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-29

Reference 20: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-29

Reference 21: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 22: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 23: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 24: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 25: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 26: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 27: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 28: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 40
-SubTopic 30
-Topic 350
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482640/350-30-55-40

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482686/350-30-45-1

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-3

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 926
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483154/926-20-50-5

+ Details

- Definition

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482548/350-20-55-24

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-8

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-41

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 740
-Name Accounting Standards Codification
-Section 55
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478064/805-740-55-13

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 39
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-39

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 49
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-49

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481372/852-10-55-10

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(15))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482598/350-20-45-1

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-1

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 14: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-4

+ Details

Atlantic Union Bankshares Corp 10-Q