Accounting Standards - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016		Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in operating activities, (Increase) decrease in other assets	$ 1.1	$ (6.2)	[1]
Increase (decrease) in other investing activities	0.3	0.2	[1]
Reclassification from operating activities, Decrease in accounts payable and other accrued liabilities	(28.3)	(35.6)	[1]
Increase (decrease) in other financing activities	(2.1)	(0.4)	[1]
Increase in effect of exchange rate changes on cash, cash equivalents and restricted cash	12.8	0.1	[1]
Cash, cash equivalents and restricted cash, beginning of period	401.1	396.8	[1]
Cash, cash equivalents and restricted cash, end of period	590.2	493.8	[1]
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from operating activities, Decrease in accounts payable and other accrued liabilities		0.4
Increase (decrease) in other financing activities		(0.4)
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net periodic benefit cost, other than service cost	$ 42.6
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in operating activities, (Increase) decrease in other assets		0.8
Increase (decrease) in other investing activities		(0.8)
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in operating activities, (Increase) decrease in other assets		(3.1)
Increase (decrease) in other investing activities		1.3
Increase in effect of exchange rate changes on cash, cash equivalents and restricted cash		0.4
Cash, cash equivalents and restricted cash, beginning of period		31.6
Cash, cash equivalents and restricted cash, end of period		$ 30.2
New Accounting Pronouncement, Early Adoption, Effect | Accumulated Deficit | Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment				$ 4.4

[1] Amounts were changed to conform to the current-year presentation. See Note 11.