CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Class A ordinary shares/ Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury shares [Member]	Accumulated other comprehensive income (loss) [Member]
Beginning Balance at Dec. 31, 2015	$ 4,772.5	$ 15.7	$ 1,458.5	$ 3,509.8	$ (12.2)	$ (199.3)
Beginning Balance (in shares) at Dec. 31, 2015		124.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net shares issued (acquired) under share-based compensation plans	(2.8)	$ 0.0	(6.6)		3.8
Net shares issued (acquired) under share-based compensation plans (in shares)		0.4
Share-based compensation	5.9		5.9
Excess tax deficit from share-based awards	(0.8)		(0.8)
Retirement benefit adjustments, net of taxes	2.5					2.5
Net income	122.8			122.8
Ending Balance at Mar. 31, 2016	4,900.1	$ 15.7	1,457.0	3,632.6	(8.4)	(196.8)
Ending Balance (in shares) at Mar. 31, 2016		125.2
Beginning Balance at Dec. 31, 2016	5,113.9	$ 16.0	1,471.7	3,830.4	(7.2)	(197.0)
Beginning Balance (in shares) at Dec. 31, 2016		125.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net shares issued (acquired) under share-based compensation plans	(5.3)	$ 0.0	(3.2)		(2.1)
Net shares issued (acquired) under share-based compensation plans (in shares)		0.6
Share-based compensation	5.4		5.4
Retirement benefit adjustments, net of taxes	0.9					0.9
Net income	10.3			10.3
Ending Balance at Mar. 31, 2017	5,331.8	$ 16.0	$ 1,473.9	4,047.3	$ (9.3)	$ (196.1)
Ending Balance (in shares) at Mar. 31, 2017		126.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard	$ 206.6			$ 206.6