v3.25.3

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Inventory, Cost Method [Extensible Enumeration]	us-gaap:CostMethodLifoMember
Inventory LIFO reserve	$ 128.0	$ 95.0
Inventories accounted under the LIFO method	88.00%	89.00%
Consignment inventory	$ 5.4	$ 5.0

Indicates method of determining cost basis for inventory. Includes, but is not limited to, first-in first-out (FIFO), last-in first-out (LIFO), and average cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 330
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483080/330-10-50-1

+ Details

Name:	us-gaap_InventoryCostMethodExtensibleEnumeration
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_InventoryDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_InventoryLIFOReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Gross amount of inventory owned by the entity but in the hands of a customer, typically a reseller.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_OtherInventoryMaterialsSuppliesAndMerchandiseUnderConsignment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfLIFOInventory
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Ryerson Holding Corp 10-Q