Commitments and Contingencies - (Details)	Sep. 30, 2018
Environmental Contingencies
Ownership interest in domestic subsidiaries (as a percent)	100.00%

Represents the parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	rs_MajorityInterestOwnershipPercentageByParent
Namespace Prefix:	rs_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant