Accumulated pretax adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

Name:	rs_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentsBeforeTax
Namespace Prefix:	rs
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended			1 Months Ended			9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Aug. 31, 2011 Officers Restricted Stock Award Member	May 31, 2011 Non-employee director restricted stock award year	Feb. 28, 2011 Stock options	Sep. 30, 2011 Stock options year
Equity
Issuance of common stock in connection with the exercise of stock options (in shares)			225,746
Total proceeds from the exercise of stock options			$ 9.6	$ 17.4
Share Based Compensation
Restricted stock granted (in shares)						86,000	16,079
Percentage of options vesting on the each anniversary (as a percent)						20.00%
Number of years from grant date that recipient is restricted from trading restricted stock (in years)							1
Fair value on the grant date (in dollars per share)						$ 37.29	$ 52.24
Stock options granted (in shares)								1,037,250
Vesting period (in years)								four years
Expiration period (in years)								seven years
Fair value of stock options granted (in dollars per share)								$ 26.98
Assumptions used in the Black-Scholes option-pricing model
Expected life (in years)									4.8
Expected volatility rate (as a percent)									60.20%
Dividend yield rate (as a percent)									0.90%
Risk free interest rate (as a percent)									2.20%
Exercise price (in dollars per share)									$ 55.73
Share Repurchase Program
Remaining number of common stock authorized for repurchase under stock repurchase program (in shares)	7,883,033		7,883,033
Other Comprehensive (Loss) Income
Net income	86.3	49.3	280.1	157.1
Other comprehensive (loss) income:
Foreign currency translation (loss) gain	(19.8)	5.4	(13.4)	4.5
Unrealized (loss) gain on investments, net of tax	(0.3)	0.1	(0.2)
Total other comprehensive (loss) income	(20.1)	5.5	(13.6)	4.5
Comprehensive income	66.2	54.8	266.5	161.6
Comprehensive income attributable to noncontrolling interests	(1.4)	(0.6)	(4.2)	(2.2)
Comprehensive income attributable to Reliance	64.8	54.2	262.3	159.4
Accumulated Other Comprehensive (Loss) Income
Foreign currency translation gain	6.9		6.9		20.3
Unrealized loss on investments, net of tax	(0.4)		(0.4)		(0.2)
Minimum pension liability, net of tax	(9.8)		(9.8)		(9.8)
Total accumulated other comprehensive (loss) income	(3.3)		(3.3)		10.3
Deferred tax assets in accumulated other comprehensive income, pension liabilities	6.6		6.6		6.6
Deferred tax assets in accumulated other comprehensive income, unrealized loss on investments	$ 0.3		$ 0.3		$ 0.1