Supplemental Guarantor Information - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) 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
Net change in accounts payable-inventory financing	0.0	(2,121.3)	(1,490.4)
Payments to extinguish long-term debt			(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)
Repayment of intercompany loan	0.0	0.0	0.0
Other	29.8	9.0	25.9
Distributions and advances from (to) affiliates	0.0	0.0	0.0
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
Reportable Legal Entities | Affiliated Entity
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	0.0	0.0	0.0
Cash flows used in investing activities:
Capital expenditures	0.0	0.0	0.0
Premium payments on interest rate cap agreements			0.0
Net cash used in investing activities	0.0	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0
Proceeds from issuance of long-term debt		0.0	0.0
Net change in accounts payable-inventory financing		0.0
Payments to extinguish long-term debt			0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0	0.0
Repayment of intercompany loan	0.0	0.0	0.0
Other	0.0	0.0	0.0
Distributions and advances from (to) affiliates	0.0	0.0	0.0
Net cash (used in) provided by financing activities	0.0	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents – beginning of period	0.0	0.0	0.0
Cash and cash equivalents – end of period	0.0	0.0	0.0
Reportable Legal Entities | Parent Guarantor
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	0.0	0.6	0.0
Cash flows used in investing activities:
Capital expenditures	0.0	0.0	0.0
Premium payments on interest rate cap agreements			0.0
Net cash used in investing activities	0.0	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0
Proceeds from issuance of long-term debt		0.0	0.0
Net change in accounts payable-inventory financing		0.0
Payments to extinguish long-term debt			0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Repurchases of common stock	(522.3)	(534.0)	(367.4)
Payment of incentive compensation plan withholding taxes	(33.9)	(49.6)
Dividends	(139.4)	(106.9)	(78.7)
Repayment of intercompany loan	0.0	0.0	0.0
Other	0.0	0.0	0.0
Distributions and advances from (to) affiliates	695.6	689.9	446.1
Net cash (used in) provided by financing activities	0.0	(0.6)	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents – beginning of period	0.0	0.0	0.0
Cash and cash equivalents – end of period	0.0	0.0	0.0
Reportable Legal Entities | Subsidiary Issuer
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	(85.7)	(71.1)	(158.5)
Cash flows used in investing activities:
Capital expenditures	(40.8)	(55.2)	(50.9)
Premium payments on interest rate cap agreements			(2.4)
Net cash used in investing activities	(40.8)	(55.2)	(53.3)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	640.0	1,501.5	329.6
Repayments of borrowings under revolving credit facility	(640.0)	(1,501.5)	(329.6)
Repayments of long-term debt	(14.9)	(14.9)	(15.2)
Proceeds from issuance of long-term debt		2,083.0	1,483.0
Net change in accounts payable-inventory financing		(2,121.3)
Payments to extinguish long-term debt			(1,490.4)
Net change in accounts payable-inventory financing	(0.8)	(0.2)	1.5
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0	0.0
Repayment of intercompany loan	0.0	0.0	0.0
Other	34.6	14.1	12.2
Distributions and advances from (to) affiliates	169.9	56.6	398.3
Net cash (used in) provided by financing activities	188.8	17.3	389.4
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net increase (decrease) in cash and cash equivalents	62.3	(109.0)	177.6
Cash and cash equivalents – beginning of period	113.7	222.7	45.1
Cash and cash equivalents – end of period	176.0	113.7	222.7
Reportable Legal Entities | Guarantor Subsidiaries
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	1,073.6	788.5	695.5
Cash flows used in investing activities:
Capital expenditures	(34.5)	(6.3)	(7.6)
Premium payments on interest rate cap agreements			0.0
Net cash used in investing activities	(34.5)	(6.3)	(7.6)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0
Proceeds from issuance of long-term debt		0.0	0.0
Net change in accounts payable-inventory financing		0.0
Payments to extinguish long-term debt			0.0
Net change in accounts payable-inventory financing	(74.7)	(78.4)	131.0
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0	0.0
Repayment of intercompany loan	47.5	34.3	40.4
Other	(4.4)	(4.0)	16.7
Distributions and advances from (to) affiliates	(1,007.5)	(737.2)	(872.9)
Net cash (used in) provided by financing activities	(1,039.1)	(785.3)	(684.8)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	(3.1)	3.1
Cash and cash equivalents – beginning of period	0.0	3.1	0.0
Cash and cash equivalents – end of period	0.0	0.0	3.1
Reportable Legal Entities | Non-Guarantor Subsidiaries
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	75.0	52.3	56.1
Cash flows used in investing activities:
Capital expenditures	(10.8)	(19.6)	(5.0)
Premium payments on interest rate cap agreements			0.0
Net cash used in investing activities	(10.8)	(19.6)	(5.0)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	46.7	59.2	9.2
Repayments of borrowings under revolving credit facility	(46.7)	(59.2)	(9.2)
Repayments of long-term debt	(6.7)	0.0	(5.4)
Proceeds from issuance of long-term debt		0.0	0.0
Net change in accounts payable-inventory financing		0.0
Payments to extinguish long-term debt			0.0
Net change in accounts payable-inventory financing	8.1	(5.4)	11.1
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0	0.0
Repayment of intercompany loan	(47.5)	(34.3)	(40.4)
Other	(0.4)	(1.1)	(3.0)
Distributions and advances from (to) affiliates	0.0	0.0	0.0
Net cash (used in) provided by financing activities	(46.5)	(40.8)	(37.7)
Effect of exchange rate changes on cash and cash equivalents	(3.4)	2.6	(7.4)
Net increase (decrease) in cash and cash equivalents	14.3	(5.5)	6.0
Cash and cash equivalents – beginning of period	32.4	37.9	31.9
Cash and cash equivalents – end of period	46.7	32.4	37.9
Consolidating Adjustments
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	(157.0)	7.4	10.9
Cash flows used in investing activities:
Capital expenditures	0.0	0.0	0.0
Premium payments on interest rate cap agreements			0.0
Net cash used in investing activities	0.0	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0
Proceeds from issuance of long-term debt		0.0	0.0
Net change in accounts payable-inventory financing		0.0
Payments to extinguish long-term debt			0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0	0.0
Repayment of intercompany loan	0.0	0.0	0.0
Other	0.0	0.0	0.0
Distributions and advances from (to) affiliates	142.0	(9.3)	28.5
Net cash (used in) provided by financing activities	142.0	(9.3)	28.5
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net increase (decrease) in cash and cash equivalents	(15.0)	(1.9)	39.4
Cash and cash equivalents – beginning of period	(1.9)	0.0	(39.4)
Cash and cash equivalents – end of period	$ (16.9)	$ (1.9)	$ 0.0