Condensed Consolidating Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities:	$ 325.1	$ 373.9	$ 353.6
Cash flows from investing activities:
Proceeds from the disposal of property, plant and equipment	0.2	0.2	0.1
Purchases of property, plant and equipment	(98.3)	(84.3)	(69.9)
Net cash used in investing activities	(98.1)	(84.1)	(69.8)
Cash flows from financing activities:
Short-term borrowings, net	(1.5)	(2.4)	(1.7)
Asset securitization borrowings	315.0	145.0	40.0
Asset securitization payments	(89.0)	(295.0)	(60.0)
Long-term debt borrowings	0.0	350.0	0.0
Borrowings from credit facility	2,376.5	2,336.5	1,671.0
Long-term debt payments	(200.9)	(58.8)	(24.0)
Payments on credit facility	(2,265.5)	(2,346.0)	(1,807.5)
Payments of deferred financing costs	(0.2)	(4.2)	0.0
Proceeds from employee stock purchases	3.1	2.6	2.4
Repurchases of common stock to satisfy employee withholding tax obligations	(26.1)	(33.3)	(32.0)
Repurchases of common stock	(250.0)	(300.0)	0.0
Excess tax benefits related to share-based payments	0.0
Intercompany debt	0.0	0.0	0.0
Intercompany financing activity	0.0	0.0	0.0
Cash dividends paid	(79.7)	(69.0)	(59.3)
Net cash used in financing activities	(218.3)	(274.6)	(271.1)
Increase (decrease) in cash and cash equivalents	8.7	15.2	12.7
Effect of exchange rates on cash and cash equivalents	9.3	(3.9)	(11.3)
Cash and cash equivalents, beginning of year	50.2	38.9	37.5
Cash and cash equivalents, end of year	68.2	50.2	38.9
Parent [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities:	467.4	17.8	249.3
Cash flows from investing activities:
Proceeds from the disposal of property, plant and equipment	0.0	0.0	0.0
Purchases of property, plant and equipment	0.0	0.0	0.0
Net cash used in investing activities	0.0	0.0	0.0
Cash flows from financing activities:
Short-term borrowings, net	0.0	0.0	0.0
Asset securitization borrowings	0.0	0.0	0.0
Asset securitization payments	0.0	0.0	0.0
Long-term debt borrowings	0.0	350.0	0.0
Borrowings from credit facility	2,376.5	2,336.5	1,671.0
Long-term debt payments	(200.0)	(57.5)	(22.5)
Payments on credit facility	(2,265.5)	(2,346.0)	(1,807.5)
Payments of deferred financing costs	0.0	(4.2)	0.0
Proceeds from employee stock purchases	3.1	2.6	2.4
Repurchases of common stock to satisfy employee withholding tax obligations	(26.1)	(33.3)	(32.0)
Repurchases of common stock	(250.0)	(300.0)	0.0
Excess tax benefits related to share-based payments	0.0
Intercompany debt	56.4	30.0	(9.4)
Intercompany financing activity	(81.7)	73.8	7.5
Cash dividends paid	(79.7)	(69.0)	(59.3)
Net cash used in financing activities	(467.0)	(17.1)	(249.8)
Increase (decrease) in cash and cash equivalents	0.4	0.7	(0.5)
Effect of exchange rates on cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents, beginning of year	1.2	0.5	1.0
Cash and cash equivalents, end of year	1.6	1.2	0.5
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities:	31.1	218.5	49.3
Cash flows from investing activities:
Proceeds from the disposal of property, plant and equipment	0.1	0.0	0.1
Purchases of property, plant and equipment	(70.7)	(71.5)	(60.2)
Net cash used in investing activities	(70.6)	(71.5)	(60.1)
Cash flows from financing activities:
Short-term borrowings, net	0.0	0.0	0.0
Asset securitization borrowings	0.0	0.0	0.0
Asset securitization payments	0.0	0.0	0.0
Long-term debt borrowings	0.0	0.0
Borrowings from credit facility	0.0	0.0	0.0
Long-term debt payments	(0.3)	(0.9)	(1.2)
Payments on credit facility	0.0	0.0	0.0
Payments of deferred financing costs	0.0	0.0	0.0
Proceeds from employee stock purchases	0.0	0.0	0.0
Repurchases of common stock to satisfy employee withholding tax obligations	0.0	0.0	0.0
Repurchases of common stock	0.0	0.0	0.0
Excess tax benefits related to share-based payments	0.0
Intercompany debt	(34.9)	(65.8)	7.1
Intercompany financing activity	85.6	(71.0)	1.2
Cash dividends paid	0.0	0.0	0.0
Net cash used in financing activities	50.4	(137.7)	7.1
Increase (decrease) in cash and cash equivalents	10.9	9.3	(3.7)
Effect of exchange rates on cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents, beginning of year	17.1	7.8	11.5
Cash and cash equivalents, end of year	28.0	17.1	7.8
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities:	(173.4)	137.6	55.0
Cash flows from investing activities:
Proceeds from the disposal of property, plant and equipment	0.1	0.2	0.0
Purchases of property, plant and equipment	(27.6)	(12.8)	(9.7)
Net cash used in investing activities	(27.5)	(12.6)	(9.7)
Cash flows from financing activities:
Short-term borrowings, net	(1.5)	(2.4)	(1.7)
Asset securitization borrowings	315.0	145.0	40.0
Asset securitization payments	(89.0)	(295.0)	(60.0)
Long-term debt borrowings	0.0	0.0
Borrowings from credit facility	0.0	0.0	0.0
Long-term debt payments	(0.6)	(0.4)	(0.3)
Payments on credit facility	0.0	0.0	0.0
Payments of deferred financing costs	(0.2)	0.0	0.0
Proceeds from employee stock purchases	0.0	0.0	0.0
Repurchases of common stock to satisfy employee withholding tax obligations	0.0	0.0	0.0
Repurchases of common stock	0.0	0.0	0.0
Excess tax benefits related to share-based payments	0.0
Intercompany debt	(21.5)	35.8	2.3
Intercompany financing activity	(3.9)	(2.8)	(8.7)
Cash dividends paid	0.0	0.0	0.0
Net cash used in financing activities	198.3	(119.8)	(28.4)
Increase (decrease) in cash and cash equivalents	(2.6)	5.2	16.9
Effect of exchange rates on cash and cash equivalents	9.3	(3.9)	(11.3)
Cash and cash equivalents, beginning of year	31.9	30.6	25.0
Cash and cash equivalents, end of year	38.6	31.9	30.6
Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities:	0.0	0.0	0.0
Cash flows from investing activities:
Proceeds from the disposal of property, plant and equipment	0.0	0.0	0.0
Purchases of property, plant and equipment	0.0	0.0	0.0
Net cash used in investing activities	0.0	0.0	0.0
Cash flows from financing activities:
Short-term borrowings, net	0.0	0.0	0.0
Asset securitization borrowings	0.0	0.0	0.0
Asset securitization payments	0.0	0.0	0.0
Long-term debt borrowings	0.0	0.0
Borrowings from credit facility	0.0	0.0	0.0
Long-term debt payments	0.0	0.0	0.0
Payments on credit facility	0.0	0.0	0.0
Payments of deferred financing costs	0.0	0.0	0.0
Proceeds from employee stock purchases	0.0	0.0	0.0
Repurchases of common stock to satisfy employee withholding tax obligations	0.0	0.0	0.0
Repurchases of common stock	0.0	0.0	0.0
Excess tax benefits related to share-based payments	0.0
Intercompany debt	0.0	0.0	0.0
Intercompany financing activity	0.0	0.0	0.0
Cash dividends paid	0.0	0.0	0.0
Net cash used in financing activities	0.0	0.0	0.0
Increase (decrease) in cash and cash equivalents	0.0	0.0	0.0
Effect of exchange rates on cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents, beginning of year	0.0	0.0	0.0
Cash and cash equivalents, end of year	$ 0.0	$ 0.0	$ 0.0