Accumulated Other Comprehensive (Loss) Income - Details of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 609.7
Other comprehensive (loss) income before reclassifications	96.4	$ (107.3)
Less: amounts reclassified from accumulated other comprehensive income (loss)	7.8	(21.8)
Other comprehensive income (loss), net of taxes	104.2	(129.1)	$ (206.2)
Balance at end of period	152.3	609.7
Intra-entity foreign currency translation adjustment	(694.4)	(701.9)
Unrecognized pension items written off	173.4
Cumulative translation adjustment written off	454.7
Unrecognized Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(276.7)	(266.0)
Other comprehensive (loss) income before reclassifications	167.1	(18.0)
Less: amounts reclassified from accumulated other comprehensive income (loss)	6.2	7.3
Other comprehensive income (loss), net of taxes	173.3	(10.7)
Balance at end of period	(103.4)	(276.7)	(266.0)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(701.9)	(564.0)
Other comprehensive (loss) income before reclassifications	7.5	(91.9)
Less: amounts reclassified from accumulated other comprehensive income (loss)	0.0	(46.0)
Other comprehensive income (loss), net of taxes	7.5	(137.9)
Balance at end of period	(694.4)	(701.9)	(564.0)
Cumulative Translation Adjustment | Intra-entity transactions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Intra-entity foreign currency translation adjustment	(78.2)	(8.3)	31.1
Unrecognized Gains (Losses) on Derivative Instruments | Net Investment Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	21.0	1.7
Other comprehensive (loss) income before reclassifications	(67.8)	19.3
Less: amounts reclassified from accumulated other comprehensive income (loss)	0.0
Other comprehensive income (loss), net of taxes	(67.8)	19.3
Balance at end of period	(46.8)	21.0	1.7
Unrecognized Gains (Losses) on Derivative Instruments | Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	8.5	8.3
Other comprehensive (loss) income before reclassifications	(10.4)	(16.7)
Less: amounts reclassified from accumulated other comprehensive income (loss)	1.6	16.9
Other comprehensive income (loss), net of taxes	(8.8)	0.2
Balance at end of period	(0.3)	8.5	8.3
Accumulated Other Comprehensive Income (Loss), Net of Taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(949.1)	(820.0)
Balance at end of period	$ (844.9)	$ (949.1)	$ (820.0)