Securities - Schedule of Credit Quality Indicators of Held-To-Maturity Securities at Amortized Cost (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	$ 0	$ 1,867,848
U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	278,383
State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	1,048,862
U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	349,726
Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	29,278
Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	161,599
AAA
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	652,633
AAA \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
AAA \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	273,629
AAA \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	349,726
AAA \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	29,278
AAA \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
AA
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	982,987
AA \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	278,383
AA \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	698,428
AA \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
AA \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
AA \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	6,176
A
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	77,628
A \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
A \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	66,079
A \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
A \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
A \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	11,549
BBB
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	86,329
BBB \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BBB \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	10,726
BBB \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BBB \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BBB \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	75,603
BB
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	4,543
BB \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BB \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BB \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BB \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
BB \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	4,543
Not Rated
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	63,728
Not Rated \| U.S. Treasury, federal agencies, and government sponsored agencies
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
Not Rated \| State and municipal
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
Not Rated \| U.S. government agency mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
Not Rated \| Private labeled mortgage-backed pools
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	0	0
Not Rated \| Corporate notes
Schedule of Held-to-Maturity Securities [Line Items]
Investment securities, held to maturity	$ 0	$ 63,728

HORIZON BANCORP INC /IN/ 10-Q