Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 store state	Dec. 31, 2011	Dec. 31, 2010
Number of stores	3,976
Number of states in which entity operates	42
Accounts receivable due from employees to the Company	$ 2,100,000	$ 2,200,000
Allowance for doubtful vendor receivables	0	0
Replacement cost of inventory	2,310,000,000	2,040,000,000
Notes receivable from vendors and other third parties	9,500,000	15,000,000
Reserve for uncollectible notes receivables	0	0
Goodwill impairment	0	0
Impairment of long-lived assets	0	0
Discount rate of self-insurance reserves	4.50%	4.75%
Self-insurance reserves, current	54,190,000	53,155,000
Instruments qualifying as cash flow or fair value hedges	0	0
Advertising expense charged to operations	74,800,000	73,800,000	70,000,000
Total interest costs capitalized	6,100,000	4,700,000	5,100,000
Deferred debt issuance costs, net of amortization	10,100,000	9,000,000
Deferred debt issuance costs, net of amortization, included in "Other current assets"	1,500,000	1,300,000
Valuation allowance for deferred tax assets	0	0
Vehicles [Member]
Gross value of capital lease assets	8,400,000	8,600,000
Accumulated amortization on capital lease assets	$ 8,400,000	$ 7,900,000
Minimum [Member]
Note receivable interest rate	0.00%
Maximum [Member]
Note receivable interest rate	10.00%