Segment Information - Summary of sales by product and service (Details)	12 Months Ended
Dec. 31, 2024 segment Y item location	Dec. 31, 2023 segment item	Dec. 31, 2022 segment item
Segment Information
Number of reportable segments	1	1	1
Number of operating segments \| segment	1	1	1
Minimum number of products the company distributes	100,000
Number of network locations \| location	320
Quarterly dividends \| Y	65
Metals Service Centers
Segment Information
Sales (as a percent)	100.00%	100.00%	100.00%
Metals Service Centers \| Carbon steel
Segment Information
Sales (as a percent)	53.00%	53.00%	54.00%
Metals Service Centers \| Aluminum
Segment Information
Sales (as a percent)	16.00%	16.00%	15.00%
Metals Service Centers \| Stainless steel
Segment Information
Sales (as a percent)	14.00%	15.00%	17.00%
Metals Service Centers \| Alloy
Segment Information
Sales (as a percent)	5.00%	5.00%	4.00%
Metals Service Centers \| Toll processing and logistics
Segment Information
Sales (as a percent)	4.00%	4.00%	3.00%
Metals Service Centers \| Copper and brass
Segment Information
Sales (as a percent)	2.00%	2.00%	2.00%
Metals Service Centers \| Miscellaneous
Segment Information
Sales (as a percent)	6.00%	5.00%	5.00%

Represents the minimum number of metal products distributed by entity.

No definition available.

Name:	rs_MinimumNumberOfMetalProductsDistributedByEntity
Namespace Prefix:	rs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of consecutive years the company has paid regular common stock quarterly dividends.

+ References

No definition available.

+ Details

Name:	rs_NumberOfConsecutiveYearsOfRegularCommonStockQuarterlyDividends
Namespace Prefix:	rs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number network locations.

+ References

No definition available.

+ Details

Name:	rs_NumberOfNetworkLocations
Namespace Prefix:	rs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of revenue from sale of goods and services.

+ References

No definition available.

+ Details

Name:	rs_SalesRevenueGoodsAndServicesNetPercentage
Namespace Prefix:	rs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: 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 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-18

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-18

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

Name:	srt_ProductOrServiceAxis=rs_AluminumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_ProductOrServiceAxis=rs_StainlessSteelMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_ProductOrServiceAxis=rs_AlloySteelMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	srt_ProductOrServiceAxis=rs_TollProcessingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=rs_CopperAndBrassMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
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