Supplemental Guarantor Information - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	$ 414.5	$ 332.3
Cash flows used in investing activities:
Capital expenditures	(43.9)	(33.6)
Acquisition of business, net of cash acquired	(75.0)	0.0
Net cash used in investing activities	(118.9)	(33.6)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	891.0	488.1
Repayments of borrowings under revolving credit facility	(815.0)	(474.4)
Repayments of long-term debt	(9.6)	(7.5)
Net change in accounts payable-inventory financing	36.3	(110.4)
Repurchases of common stock	(332.2)	(176.4)
Payment of incentive compensation plan withholding taxes	(11.6)	(8.7)
Dividend payments	(86.3)	(63.8)
Capital contributions	0.0	0.0
Other	22.2	14.9
Distributions and advances from (to) affiliates	0.0	0.0
Net cash used in financing activities	(305.2)	(338.2)
Effect of exchange rate changes on cash and cash equivalents	(1.7)	(4.0)
Net decrease in cash and cash equivalents	(11.3)	(43.5)
Cash and cash equivalents—beginning of period	205.8	144.2
Cash and cash equivalents—end of period	194.5	100.7
Consolidating Adjustments
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	10.7	(14.0)
Cash flows used in investing activities:
Capital expenditures	0.0	0.0
Acquisition of business, net of cash acquired	0.0
Net cash used in investing activities	0.0	0.0
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0
Repayments of long-term debt	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividend payments	0.0	0.0
Capital contributions	0.0	0.0
Other	0.0	0.0
Distributions and advances from (to) affiliates	6.2	(6.7)
Net cash used in financing activities	6.2	(6.7)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net decrease in cash and cash equivalents	16.9	(20.7)
Cash and cash equivalents—beginning of period	(16.9)	(1.9)
Cash and cash equivalents—end of period	0.0	(22.6)
Parent Guarantor
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	0.0
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 facility	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0
Repayments of long-term debt	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0
Repurchases of common stock	(332.2)	(176.4)
Payment of incentive compensation plan withholding taxes	(11.6)	(8.7)
Dividend payments	(86.3)	(63.8)
Capital contributions	0.0	0.0
Other	0.0	0.0
Distributions and advances from (to) affiliates	430.1	248.9
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 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
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	0.0
Subsidiary Issuer | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	(7.0)	(71.8)
Cash flows used in investing activities:
Capital expenditures	(31.2)	(24.2)
Net cash used in investing activities	(31.2)	(24.2)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	891.0	467.5
Repayments of borrowings under revolving credit facility	(815.0)	(467.5)
Repayments of long-term debt	(7.5)	(7.5)
Net change in accounts payable-inventory financing	0.3	(0.9)
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividend payments	0.0	0.0
Capital contributions	(76.0)	0.0
Other	22.4	15.3
Distributions and advances from (to) affiliates	(55.4)	46.3
Net cash used in financing activities	(40.2)	53.2
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net decrease in cash and cash equivalents	(78.4)	(42.8)
Cash and cash equivalents—beginning of period	176.0	113.7
Cash and cash equivalents—end of period	97.6	70.9
Guarantor Subsidiaries
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	0.0
Guarantor Subsidiaries | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	317.0	343.9
Cash flows used in investing activities:
Capital expenditures	(8.0)	(1.9)
Net cash used in investing activities	(8.0)	(1.9)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0
Repayments of long-term debt	0.0	0.0
Net change in accounts payable-inventory financing	45.1	(100.8)
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividend payments	0.0	0.0
Capital contributions	0.0	47.5
Other	(0.2)	(0.2)
Distributions and advances from (to) affiliates	(330.1)	(288.5)
Net cash used in financing activities	(285.2)	(342.0)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net decrease in cash and cash equivalents	23.8	0.0
Cash and cash equivalents—beginning of period	0.0	0.0
Cash and cash equivalents—end of period	23.8	0.0
Non-Guarantor Subsidiaries
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	(75.0)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Supplemental Guarantor Information [Line Items]
Net cash provided by operating activities	93.8	74.2
Cash flows used in investing activities:
Capital expenditures	(4.7)	(7.5)
Net cash used in investing activities	(79.7)	(7.5)
Cash flows used in financing activities:
Proceeds from borrowings under revolving credit facility	0.0	20.6
Repayments of borrowings under revolving credit facility	0.0	(6.9)
Repayments of long-term debt	(2.1)	0.0
Net change in accounts payable-inventory financing	(9.1)	(8.7)
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividend payments	0.0	0.0
Capital contributions	76.0	(47.5)
Other	0.0	(0.2)
Distributions and advances from (to) affiliates	(50.8)	0.0
Net cash used in financing activities	14.0	(42.7)
Effect of exchange rate changes on cash and cash equivalents	(1.7)	(4.0)
Net decrease in cash and cash equivalents	26.4	20.0
Cash and cash equivalents—beginning of period	46.7	32.4
Cash and cash equivalents—end of period	73.1	52.4
Affiliated Entity
Cash flows used in investing activities:
Acquisition of business, net of cash acquired	0.0
Affiliated Entity | 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 facility	0.0	0.0
Repayments of borrowings under revolving credit facility	0.0	0.0
Repayments of long-term debt	0.0	0.0
Net change in accounts payable-inventory financing	0.0	0.0
Repurchases of common stock	0.0	0.0
Payment of incentive compensation plan withholding taxes	0.0	0.0
Dividend payments	0.0	0.0
Capital contributions	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 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