Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net income	$ 1,324,487	$ 1,133,804	$ 1,037,691
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	258,937	233,845	217,866
Amortization of debt discount and issuance costs	3,470	2,871	2,451
Deferred income taxes	20,160	(4,593)	10,394
Share-based compensation programs	20,176	19,401	18,859
Other	9,895	11,790	6,434
Changes in operating assets and liabilities:
Accounts receivable	18,138	(27,742)	(38,548)
Inventory	(163,367)	(231,802)	(119,270)
Accounts payable	177,676	253,265	322,427
Income taxes payable	22,903	14,220	26,880
Accrued payroll	9,373	5,430	12,616
Accrued benefits and withholdings	28,022	3,042	(256)
Other	(2,315)	(9,844)	13,169
Net cash provided by operating activities	1,727,555	1,403,687	1,510,713
Investing activities:
Purchases of property and equipment	(504,268)	(465,940)	(476,344)
Proceeds from sale of property and equipment	4,784	4,464	5,119
Payments received on notes receivable	0	0	1,047
Other	(34,818)	(2,747)	(58,918)
Net cash used in investing activities	(534,302)	(464,223)	(529,096)
Financing activities:
Proceeds from borrowings on revolving credit facility	2,414,000	3,101,000	0
Payments on revolving credit facility	(2,473,000)	(2,755,000)	0
Proceeds from the issuance of long-term debt	498,660	748,800	499,160
Payment of debt issuance costs	(3,923)	(7,590)	(4,125)
Repurchases of common stock	(1,714,013)	(2,172,530)	(1,505,437)
Net proceeds from issuance of common stock	72,146	45,762	59,634
Other	(2,156)	(156)	(552)
Net cash used in financing activities	(1,208,286)	(1,039,714)	(951,320)
Net (decrease) increase in cash and cash equivalents	(15,033)	(100,250)	30,297
Cash and cash equivalents at beginning of the year	46,348	146,598	116,301
Cash and cash equivalents at end of the year	31,315	46,348	146,598
Supplemental disclosures of cash flow information:
Income taxes paid	311,376	496,728	569,677
Interest paid, net of capitalized interest	$ 117,938	$ 77,766	$ 63,648