Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017
Operating activities:
Net income	$ 1,024,130		$ 831,489
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	193,318		173,500
Amortization of debt discount and issuance costs	2,557		2,078
Deferred income taxes	17,234		41,848
Share-based compensation programs	15,144		14,835
Other	6,304		8,174
Changes in operating assets and liabilities:
Accounts receivable	(32,799)		(28,761)
Inventory	(129,214)		(208,338)
Accounts payable	194,069		217,486
Income taxes payable	4,460		32,124
Other	46,816		2,984
Net cash provided by operating activities	1,342,019		1,087,419
Investing activities:
Purchases of property and equipment	(350,461)		(347,756)
Proceeds from sale of property and equipment	3,353		1,906
Other	(716)		(2,072)
Net cash used in investing activities	(347,824)		(347,922)
Financing activities:
Proceeds from borrowings on revolving credit facility	1,745,000		2,487,000
Payments on revolving credit facility	(2,046,000)		(2,218,000)
Proceeds from issuance of long-term debt	498,660		748,800
Payments of debt issuance costs	(3,923)		(7,490)
Repurchases of common stock	(1,251,060)		(1,893,148)
Net proceeds from issuance of common stock	58,955		34,186
Other	(2,156)		(156)
Net cash used in financing activities	(1,000,524)		(848,808)
Net decrease in cash and cash equivalents	(6,329)		(109,311)
Cash and cash equivalents at beginning of the period	46,348	[1]	146,598
Cash and cash equivalents at end of the period	40,019		37,287
Supplemental disclosures of cash flow information:
Income taxes paid	256,949		359,838
Interest paid, net of capitalized interest	$ 102,025		$ 72,252

[1] The balance sheet at December 31, 2017, 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.