Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 Rate states stores	Dec. 31, 2013	Dec. 31, 2012
Policy Text Block [Abstract]
Number of stores	4,366
Number of states in which entity operates	43
Accounts receivable due from employees to the Company	$ 1,000,000	$ 1,000,000
Allowance for doubtful supplier receivables	0	0
Replacement cost of inventory	2,560,000,000	2,380,000,000
LIFO inventory value in excess of replacement cost of inventory	61,400,000	21,600,000
Notes receivable from suppliers and other third parties	17,500,000	17,200,000
Reserve for uncollectable notes receivables	0	0
Note receivable interest rate	0.00%
Goodwill impairment	0	0
Impairment of long-lived assets	0	0
Self-insurance reserves, current	64,882,000	57,700,000
Advertising expense, net	79,000,000	78,300,000	74,800,000
Total interest costs capitalized	11,500,000	10,600,000	6,100,000
Deferred debt issuance costs, net of amortization	9,900,000	11,500,000
Deferred debt issuance costs, net of amortization, included in "Other current assets"	1,600,000	1,600,000
Original issuance discounts, net of accretion	3,400,000	3,900,000
Valuation allowance for deferred tax assets	$ 0	$ 0