Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018
Operating activities:
Net income	$ 674,833		$ 657,979
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	132,275		130,792
Amortization of debt discount and issuance costs	1,887		1,649
Deferred income taxes	8,364		9,024
Share-based compensation programs	11,015		10,152
Other	4,277		4,653
Changes in operating assets and liabilities:
Accounts receivable	(74,978)		(29,550)
Inventory	(69,103)		(81,614)
Accounts payable	138,522		124,642
Income taxes payable	(833)		26,439
Other	20,745		21,067
Net cash provided by operating activities	847,004		875,233
Investing activities:
Purchases of property and equipment	(295,608)		(224,117)
Proceeds from sale of property and equipment	3,138		2,936
Investment in tax credit equity investments	(1,717)		0
Return on tax credit equity investments	127		0
Other	712		(424)
Net cash used in investing activities	(293,348)		(221,605)
Financing activities:
Proceeds from borrowings on revolving credit facility	1,629,000		1,429,000
Payments on revolving credit facility	(1,760,000)		(1,650,000)
Proceeds from the issuance of long-term debt	499,955		498,660
Payments of debt issuance costs	(3,988)		(3,923)
Repurchases of common stock	(920,717)		(965,867)
Net proceeds from issuance of common stock	26,778		31,178
Other	(190)		(2,156)
Net cash used in financing activities	(529,162)		(663,108)
Net increase (decrease) in cash and cash equivalents	24,494		(9,480)
Cash and cash equivalents at beginning of the period	31,315	[1]	46,348
Cash and cash equivalents at end of the period	55,809		36,868
Supplemental disclosures of cash flow information:
Income taxes paid	194,503		150,990
Interest paid, net of capitalized interest	$ 64,201		$ 55,556

[1] The balance sheet at December 31, 2018, 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.