CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 43.6	$ 60.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	25.7	22.6
Amortization	0.7	0.7
Stock-based compensation	3.4	3.5
Non-cash restructuring charges	0.1	0.0
Contingent consideration payments in excess of acquisition-date liability	(0.2)	0.0
Other non-cash items, net	(2.7)	(3.2)
Changes in assets and liabilities	(25.6)	(63.8)
Net cash provided by operating activities	45.0	20.7
Cash flows from investing activities:
Capital expenditures	(28.0)	(37.5)
Other, net	(0.7)	2.8
Net cash used in investing activities	(28.7)	(34.7)
Cash flows from financing activities:
Repayments of long-term debt	0.0	(0.6)
Dividend payments	(10.4)	(9.5)
Contingent consideration payments up to amount of acquisition-date liability	0.0	(0.1)
Proceeds from exercise of stock options and stock appreciation rights	4.0	18.1
Employee stock purchase plan contributions	1.1	1.0
Shares purchased under share repurchase programs	(47.9)	(26.9)
Shares repurchased for employee tax withholdings	(3.7)	(3.8)
Net cash used in financing activities	(56.9)	(21.8)
Effect of exchange rates on cash	4.5	2.2
Net decrease in cash and cash equivalents	(36.1)	(33.6)
Cash and cash equivalents at beginning of period	235.9	203.0
Cash and cash equivalents at end of period	$ 199.8	$ 169.4