CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - 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	(4.3)	$ 0.0	(9.3)		5.0
Net shares issued (acquired) under share-based compensation plans (in shares)		0.6
Share-based compensation	11.5		11.5
Excess tax benefit from share-based awards	2.6		2.6
Retirement benefit adjustments, net of taxes	5.0					5.0
Net income (loss)	339.5			339.5
Ending Balance at Jun. 30, 2016	5,126.8	$ 15.7	1,463.3	3,849.3	(7.2)	(194.3)
Ending Balance (in shares) at Jun. 30, 2016		125.4
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	(4.3)	$ 0.0	(2.2)		(2.1)
Net shares issued (acquired) under share-based compensation plans (in shares)		0.7
Share-based compensation	10.6		10.6
Retirement benefit adjustments, net of taxes	1.7					1.7
Net income (loss)	(18.4)			(18.4)
Ending Balance at Jun. 30, 2017	5,310.1	$ 16.0	$ 1,480.1	4,018.6	$ (9.3)	$ (195.3)
Ending Balance (in shares) at Jun. 30, 2017		126.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard	$ 206.6			$ 206.6