Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ 1,037,691	$ 931,216	$ 778,182
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	217,866	210,256	194,205
Amortization of debt discount and issuance costs	2,451	2,106	2,086
Excess tax benefit from share-based compensation	(55,994)	(63,078)	(49,150)
Deferred income taxes	10,394	(22,650)	1,487
Share-based compensation programs	18,859	21,899	23,095
Other	6,434	6,839	5,592
Changes in operating assets and liabilities:
Accounts receivable	(38,548)	(23,858)	(19,271)
Inventory	(119,270)	(76,226)	(179,742)
Accounts payable	322,427	191,064	360,646
Income taxes payable	26,880	81,617	32,158
Accrued payroll	12,616	(19,341)	12,923
Accrued benefits and withholdings	(808)	17,970	28,899
Other	13,169	23,662	(680)
Net cash provided by operating activities	1,454,167	1,281,476	1,190,430
Investing activities:
Purchases of property and equipment	(476,344)	(414,020)	(429,987)
Proceeds from sale of property and equipment	5,119	2,758	2,880
Payments received on notes receivable	1,047	4,074	3,705
Other	(58,918)	0	0
Net cash used in investing activities	(529,096)	(407,188)	(423,402)
Financing activities:
Proceeds from the issuance of long-term debt	499,160	0	0
Payment of debt issuance costs	(4,125)	0	0
Principal payments on capital leases	0	(25)	(72)
Repurchases of common stock	(1,505,437)	(1,136,213)	(866,484)
Excess tax benefit from share-based compensation	55,994	63,078	49,150
Net proceeds from issuance of common stock	59,634	64,613	69,620
Net cash used in financing activities	(894,774)	(1,008,547)	(747,786)
Net increase (decrease) in cash and cash equivalents	30,297	(134,259)	19,242
Cash and cash equivalents at beginning of the year	116,301	250,560	231,318
Cash and cash equivalents at end of the year	146,598	116,301	250,560
Supplemental disclosures of cash flow information:
Income taxes paid	569,677	485,824	416,458
Interest paid, net of capitalized interest	$ 63,648	$ 55,061	$ 51,203