Supplemental Guarantor Information - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	$ 222.2	$ 369.9
Cash flows used in investing activities:
Capital expenditures	(15.9)	(19.6)
Net cash used in investing activities	(15.9)	(19.6)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	170.0	44.1
Repayments of borrowings under revolving credit facilities	(170.0)	(6.1)
Repayments of long-term debt	(3.7)	(3.7)
Proceeds from issuance of long-term debt	0.0	2,083.0
Payments to extinguish long-term debt	0.0	(2,121.3)
Payments of debt financing costs	0.0	(9.6)
Net change in accounts payable-inventory financing	24.9	(135.7)
Premium payments on interest rate cap agreements	(12.6)	0.0
Proceeds from stock option exercises	7.3	4.4
Proceeds from Coworker Stock Purchase Plan	2.4	2.1
Repurchases of common stock	(109.2)	(175.4)
Payment of incentive compensation plan withholding taxes	(8.7)	(18.3)
Dividends	(32.0)	(25.5)
Other	0.4	(0.2)
Distributions and advances from (to) affiliates	0.0	0.0
Net cash used in financing activities	(131.2)	(362.2)
Effect of exchange rate changes on cash and cash equivalents	1.7	(0.1)
Net increase (decrease) in cash and cash equivalents	76.8	(12.0)
Cash and cash equivalents—beginning of period	144.2	263.7
Cash and cash equivalents—end of period	221.0	251.7
Consolidating Adjustments
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	(14.4)	(26.0)
Cash flows used in investing activities:
Capital expenditures	0.0	0.0
Net cash used in investing activities	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	0.0	0.0
Repayments of borrowings under revolving credit facilities	0.0	0.0
Repayments of long-term debt	0.0	0.0
Proceeds from issuance of long-term debt		0.0
Payments to extinguish long-term debt		0.0
Payments of debt financing costs		0.0
Net change in accounts payable-inventory financing	0.0	0.0
Premium payments on interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0
Other	0.0	0.0
Distributions and advances from (to) affiliates	(1.9)	2.4
Net cash used in financing activities	(1.9)	2.4
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	(16.3)	(23.6)
Cash and cash equivalents—beginning of period	(1.9)	0.0
Cash and cash equivalents—end of period	(18.2)	(23.6)
Parent Guarantor | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	0.0	0.0
Cash flows used in investing activities:
Capital expenditures	0.0	0.0
Net cash used in investing activities	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	0.0	0.0
Repayments of borrowings under revolving credit facilities	0.0	0.0
Repayments of long-term debt	0.0	0.0
Proceeds from issuance of long-term debt		0.0
Payments to extinguish long-term debt		0.0
Payments of debt financing costs		0.0
Net change in accounts payable-inventory financing	0.0	0.0
Premium payments on interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0
Repurchases of common stock	(109.2)	(175.4)
Payment of incentive compensation plan withholding taxes	(8.7)	0.0
Dividends	(32.0)	(25.5)
Other	0.0	0.0
Distributions and advances from (to) affiliates	149.9	200.9
Net cash used in financing activities	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents—beginning of period	0.0	0.0
Cash and cash equivalents—end of period	0.0	0.0
Subsidiary Issuer | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	(13.8)	24.5
Cash flows used in investing activities:
Capital expenditures	(11.1)	(14.6)
Net cash used in investing activities	(11.1)	(14.6)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	163.0	38.0
Repayments of borrowings under revolving credit facilities	(163.0)	0.0
Repayments of long-term debt	(3.7)	(3.7)
Proceeds from issuance of long-term debt		2,083.0
Payments to extinguish long-term debt		(2,121.3)
Payments of debt financing costs		(9.6)
Net change in accounts payable-inventory financing	(0.9)	(0.9)
Premium payments on interest rate cap agreements	(12.6)
Proceeds from stock option exercises	7.3	4.4
Proceeds from Coworker Stock Purchase Plan	2.4	2.1
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	(10.4)
Dividends	0.0	0.0
Other	0.7	0.0
Distributions and advances from (to) affiliates	91.3	(9.3)
Net cash used in financing activities	84.5	(27.7)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	59.6	(17.8)
Cash and cash equivalents—beginning of period	113.7	222.7
Cash and cash equivalents—end of period	173.3	204.9
Guarantor Subsidiaries
Cash flows used in financing activities:
Payments of debt financing costs		0.0
Guarantor Subsidiaries | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	239.6	333.2
Cash flows used in investing activities:
Capital expenditures	(1.2)	(2.4)
Net cash used in investing activities	(1.2)	(2.4)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	0.0	0.0
Repayments of borrowings under revolving credit facilities	0.0	0.0
Repayments of long-term debt	0.0	0.0
Proceeds from issuance of long-term debt		0.0
Payments to extinguish long-term debt		0.0
Net change in accounts payable-inventory financing	1.0	(132.2)
Premium payments on interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	(7.7)
Dividends	0.0	0.0
Other	(0.1)	0.0
Distributions and advances from (to) affiliates	(239.3)	(194.0)
Net cash used in financing activities	(238.4)	(333.9)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	(3.1)
Cash and cash equivalents—beginning of period	0.0	3.1
Cash and cash equivalents—end of period	0.0	0.0
Non-Guarantor Subsidiaries | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	10.8	38.2
Cash flows used in investing activities:
Capital expenditures	(3.6)	(2.6)
Net cash used in investing activities	(3.6)	(2.6)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	7.0	6.1
Repayments of borrowings under revolving credit facilities	(7.0)	(6.1)
Repayments of long-term debt	0.0	0.0
Proceeds from issuance of long-term debt		0.0
Payments to extinguish long-term debt		0.0
Payments of debt financing costs		0.0
Net change in accounts payable-inventory financing	24.8	(2.6)
Premium payments on interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	(0.2)
Dividends	0.0	0.0
Other	(0.2)	(0.2)
Distributions and advances from (to) affiliates	0.0	0.0
Net cash used in financing activities	24.6	(3.0)
Effect of exchange rate changes on cash and cash equivalents	1.7	(0.1)
Net increase (decrease) in cash and cash equivalents	33.5	32.5
Cash and cash equivalents—beginning of period	32.4	37.9
Cash and cash equivalents—end of period	65.9	70.4
Co-Issuer | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	0.0	0.0
Cash flows used in investing activities:
Capital expenditures	0.0	0.0
Net cash used in investing activities	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facilities	0.0	0.0
Repayments of borrowings under revolving credit facilities	0.0	0.0
Repayments of long-term debt	0.0	0.0
Proceeds from issuance of long-term debt		0.0
Payments to extinguish long-term debt		0.0
Payments of debt financing costs		0.0
Net change in accounts payable-inventory financing	0.0	0.0
Premium payments on interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividends	0.0	0.0
Other	0.0	0.0
Distributions and advances from (to) affiliates	0.0	0.0
Net cash used in financing activities	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents—beginning of period	0.0	0.0
Cash and cash equivalents—end of period	$ 0.0	$ 0.0