Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015
Operating activities:
Net income	$ 513,168		$ 446,372
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	106,430		106,007
Amortization of debt discount and issuance costs	1,173		1,051
Excess tax benefit from share-based compensation	(30,136)		(32,947)
Deferred income taxes	(6,811)		(15,326)
Share-based compensation programs	9,853		11,304
Other	2,655		2,594
Changes in operating assets and liabilities:
Accounts receivable	(28,837)		(34,199)
Inventory	(110,015)		(6,186)
Accounts payable	306,410		118,804
Income taxes payable	25,170		79,172
Other	9,333		21,807
Net cash provided by operating activities	798,393		698,453
Investing activities:
Purchases of property and equipment	(220,416)		(186,531)
Proceeds from sale of property and equipment	1,971		1,608
Payments received on notes receivable	1,047		1,981
Net cash used in investing activities	(217,398)		(182,942)
Financing activities:
Proceeds from the issuance of long-term debt	499,160		0
Payments of debt issuance costs	(3,784)		0
Principal payments on capital leases	0		(25)
Repurchases of common stock	(856,845)		(574,972)
Excess tax benefit from share-based compensation	30,136		32,947
Net proceeds from issuance of common stock	32,296		36,021
Net cash used in financing activities	(299,037)		(506,029)
Net increase in cash and cash equivalents	281,958		9,482
Cash and cash equivalents at beginning of the period	116,301	[1]	250,560
Cash and cash equivalents at end of the period	398,259		260,042
Supplemental disclosures of cash flow information:
Income taxes paid	279,099		194,715
Interest paid, net of capitalized interest	$ 27,174		$ 27,711

[1] The balance sheet at December 31, 2015, has been derived from the audited consolidated financial statements at that date, but does not include all of the information and footnotes required by United States generally accepted accounting principles for complete financial statements.