Other Income (Expense), net - Details of Other Income (Expense), Net (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Income And Expenses [Abstract]
Interest and dividend income	$ 3.3	$ 3.0	$ 6.5	$ 6.6
Net foreign exchange transaction gains (losses)	3.1	(2.6)	2.6	(4.6)
Bank fee expense	(1.3)	(1.7)	(2.4)	(3.3)
Net gain on disposals of property and equipment and other	0.5		3.8
Other, net	1.4	(3.5)	2.4	(3.1)
Other income (expense), net	$ 7.0	$ (4.8)	$ 12.9	$ (4.4)