Supplemental Guarantor Information - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	$ 777.7	$ 604.0	$ 277.5
Cash flows used in investing activities:
Capital expenditures	(81.1)	(63.5)	(90.1)
Premium payments on interest rate cap agreements	0.0	(2.4)	(0.5)
Acquisition of business, net of cash acquired	0.0	0.0	(263.8)
Net cash used in investing activities	(81.1)	(65.9)	(354.4)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	1,560.7	338.8	314.5
Repayments of borrowings under revolving credit facility	(1,560.7)	(338.8)	(314.5)
Repayments of long-term debt	(14.9)	(20.6)	(32.8)
Proceeds from issuance of long-term debt	2,083.0	1,483.0	525.0
Payments to extinguish long-term debt	(2,121.3)	(1,490.4)	(525.3)
Net change in other long-term obligation	(3.8)	15.7	0.0
Payment of debt financing costs	(9.6)	(5.9)	(6.8)
Net change in accounts payable-inventory financing	(84.0)	143.6	95.9
Effective portion of interest rate cap agreements	0.4	0.0	0.0
Proceeds from stock option exercises	13.0	7.4	2.4
Proceeds from Coworker Stock Purchase Plan	10.3	9.3	8.7
Repurchases of common stock	(534.0)	(367.4)	(241.3)
Payment of incentive compensation plan withholding taxes	(49.6)	0.0	(0.6)
Dividends	(106.9)	(78.7)	(52.9)
Principal payments under capital lease obligations	(1.3)	(0.6)
Repayment of intercompany loan	0.0	0.0
Distributions and advances from (to) affiliates	0.0	0.0	0.0
Net cash (used in) provided by financing activities	(818.7)	(304.6)	(226.5)
Effect of exchange rate changes on cash and cash equivalents	2.6	(7.4)	(3.5)
Net (decrease) increase in cash and cash equivalents	(119.5)	226.1	(306.9)
Cash and cash equivalents – beginning of period	263.7	37.6	344.5
Cash and cash equivalents – end of period	144.2	263.7	37.6
Reportable Legal Entities | Parent Guarantor
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	0.6	0.0	0.5
Cash flows used in investing activities:
Capital expenditures	0.0	0.0	0.0
Premium payments on interest rate cap agreements		0.0	0.0
Acquisition of business, net of cash acquired			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	0.0
Payments to extinguish long-term debt	0.0	0.0	0.0
Net change in other long-term obligation	0.0	0.0
Payment of debt financing costs	0.0	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Effective portion of interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	0.0	0.0	0.0
Repurchases of common stock	(534.0)	(367.4)	(241.3)
Payment of incentive compensation plan withholding taxes	(49.6)		0.0
Dividends	(106.9)	(78.7)	(52.9)
Principal payments under capital lease obligations	0.0	0.0
Repayment of intercompany loan	0.0	0.0
Distributions and advances from (to) affiliates	689.9	446.1	293.7
Net cash (used in) provided by financing activities	(0.6)	0.0	(0.5)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net (decrease) increase 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	(71.1)	(158.5)	(18.1)
Cash flows used in investing activities:
Capital expenditures	(55.2)	(50.9)	(75.4)
Premium payments on interest rate cap agreements		(2.4)	(0.5)
Acquisition of business, net of cash acquired			0.0
Net cash used in investing activities	(55.2)	(53.3)	(75.9)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	1,501.5	329.6	314.5
Repayments of borrowings under revolving credit facility	(1,501.5)	(329.6)	(314.5)
Repayments of long-term debt	(14.9)	(15.2)	(15.4)
Proceeds from issuance of long-term debt	2,083.0	1,483.0	525.0
Payments to extinguish long-term debt	(2,121.3)	(1,490.4)	(525.3)
Net change in other long-term obligation	0.0	0.0
Payment of debt financing costs	(9.6)	(4.5)	(6.8)
Net change in accounts payable-inventory financing	(0.2)	1.5	0.0
Effective portion of interest rate cap agreements	0.4
Proceeds from stock option exercises	13.0	7.4	2.4
Proceeds from Coworker Stock Purchase Plan	10.3	9.3	8.7
Repurchases of common stock	0.0	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0		(0.6)
Dividends	0.0	0.0	0.0
Principal payments under capital lease obligations	0.0	0.0
Repayment of intercompany loan	0.0	0.0
Distributions and advances from (to) affiliates	56.6	398.3	(196.5)
Net cash (used in) provided by financing activities	17.3	389.4	(207.3)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	(109.0)	177.6	(301.3)
Cash and cash equivalents – beginning of period	222.7	45.1	346.4
Cash and cash equivalents – end of period	113.7	222.7	45.1
Reportable Legal Entities | Guarantor Subsidiaries
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	788.5	695.5	350.0
Cash flows used in investing activities:
Capital expenditures	(6.3)	(7.6)	(11.6)
Premium payments on interest rate cap agreements		0.0	0.0
Acquisition of business, net of cash acquired			0.0
Net cash used in investing activities	(6.3)	(7.6)	(11.6)
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	0.0
Payments to extinguish long-term debt	0.0	0.0	0.0
Net change in other long-term obligation	(3.8)	15.7
Payment of debt financing costs	0.0	0.0	0.0
Net change in accounts payable-inventory financing	(78.4)	131.0	96.1
Effective portion of interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	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
Principal payments under capital lease obligations	(0.2)	1.0
Repayment of intercompany loan	34.3	40.4
Distributions and advances from (to) affiliates	(737.2)	(872.9)	(434.5)
Net cash (used in) provided by financing activities	(785.3)	(684.8)	(338.4)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	(3.1)	3.1	0.0
Cash and cash equivalents – beginning of period	3.1	0.0	0.0
Cash and cash equivalents – end of period	0.0	3.1	0.0
Reportable Legal Entities | Non-Guarantor Subsidiaries
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	52.3	56.1	27.9
Cash flows used in investing activities:
Capital expenditures	(19.6)	(5.0)	(3.1)
Premium payments on interest rate cap agreements		0.0	0.0
Acquisition of business, net of cash acquired			(263.8)
Net cash used in investing activities	(19.6)	(5.0)	(266.9)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	59.2	9.2	0.0
Repayments of borrowings under revolving credit facility	(59.2)	(9.2)	0.0
Repayments of long-term debt	0.0	(5.4)	(17.4)
Proceeds from issuance of long-term debt	0.0	0.0	0.0
Payments to extinguish long-term debt	0.0	0.0	0.0
Net change in other long-term obligation	0.0	0.0
Payment of debt financing costs	0.0	(1.4)	0.0
Net change in accounts payable-inventory financing	(5.4)	11.1	(0.2)
Effective portion of interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	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
Principal payments under capital lease obligations	(1.1)	(1.6)
Repayment of intercompany loan	(34.3)	(40.4)
Distributions and advances from (to) affiliates	0.0	0.0	267.4
Net cash (used in) provided by financing activities	(40.8)	(37.7)	249.8
Effect of exchange rate changes on cash and cash equivalents	2.6	(7.4)	(3.5)
Net (decrease) increase in cash and cash equivalents	(5.5)	6.0	7.3
Cash and cash equivalents – beginning of period	37.9	31.9	24.6
Cash and cash equivalents – end of period	32.4	37.9	31.9
Reportable Legal Entities | Co-Issuer
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	0.0
Acquisition of business, net of cash acquired			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	0.0
Payments to extinguish long-term debt	0.0	0.0	0.0
Net change in other long-term obligation	0.0	0.0
Payment of debt financing costs	0.0	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Effective portion of interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	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
Principal payments under capital lease obligations	0.0	0.0
Repayment of intercompany loan	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 (decrease) increase 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
Consolidating Adjustments
Supplemental Guarantor Information [Line Items]
Net cash provided by (used in) operating activities	7.4	10.9	(82.8)
Cash flows used in investing activities:
Capital expenditures	0.0	0.0	0.0
Premium payments on interest rate cap agreements		0.0	0.0
Acquisition of business, net of cash acquired			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	0.0
Payments to extinguish long-term debt	0.0	0.0	0.0
Net change in other long-term obligation	0.0	0.0
Payment of debt financing costs	0.0	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0	0.0
Effective portion of interest rate cap agreements	0.0
Proceeds from stock option exercises	0.0	0.0	0.0
Proceeds from Coworker Stock Purchase Plan	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
Principal payments under capital lease obligations	0.0	0.0
Repayment of intercompany loan	0.0	0.0
Distributions and advances from (to) affiliates	(9.3)	28.5	69.9
Net cash (used in) provided by financing activities	(9.3)	28.5	69.9
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	(1.9)	39.4	(12.9)
Cash and cash equivalents – beginning of period	0.0	(39.4)	(26.5)
Cash and cash equivalents – end of period	$ (1.9)	$ 0.0	$ (39.4)