Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net income	$ 643.0	$ 523.1	$ 425.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	265.6	260.9	254.5
Equity-based compensation expense	40.7	43.7	39.2
Deferred income taxes	(56.1)	(172.7)	(97.2)
Net loss on extinguishments of long-term debt	0.0	57.4	2.1
Other	10.9	5.0	4.3
Changes in assets and liabilities:
Accounts receivable	(365.1)	(136.8)	(178.9)
Merchandise inventory	(46.8)	16.9	(68.0)
Other assets	25.2	(117.8)	(51.8)
Accounts payable-trade	271.2	231.5	225.1
Other liabilities	117.3	66.5	49.6
Net cash provided by operating activities	905.9	777.7	604.0
Cash flows used in investing activities:
Capital expenditures	(86.1)	(81.1)	(63.5)
Premium payments on interest rate cap agreements	0.0	0.0	(2.4)
Net cash used in investing activities	(86.1)	(81.1)	(65.9)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	686.7	1,560.7	338.8
Repayments of borrowings under revolving credit facility	(686.7)	(1,560.7)	(338.8)
Repayments of long-term debt	(21.6)	(14.9)	(20.6)
Proceeds from issuance of long-term debt	0.0	2,083.0	1,483.0
Payments to extinguish long-term debt	0.0	(2,121.3)	(1,490.4)
Net change in accounts payable-inventory financing	(67.4)	(84.0)	143.6
Repurchases of common stock	(522.3)	(534.0)	(367.4)
Payment of incentive compensation plan withholding taxes	(33.9)	(49.6)	0.0
Dividends	(139.4)	(106.9)	(78.7)
Other	29.8	9.0	25.9
Net cash (used in) provided by financing activities	(754.8)	(818.7)	(304.6)
Effect of exchange rate changes on cash and cash equivalents	(3.4)	2.6	(7.4)
Net increase (decrease) in cash and cash equivalents	61.6	(119.5)	226.1
Cash and cash equivalents – beginning of period	144.2	263.7	37.6
Cash and cash equivalents – end of period	205.8	144.2	263.7
Supplementary disclosure of cash flow information:
Interest paid	(148.8)	(148.5)	(144.3)
Taxes paid, net	$ (261.2)	$ (275.7)	$ (329.2)