Earnings Per Share (Calculation of EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Income from continuing operations, net of taxes	$ 475.9	$ (368.5)	$ 86.6	$ 409.5	$ 283.4	$ 477.1	$ 164.1	$ 412.9	$ 603.5	$ 1,337.5	$ 3,282.8
(Loss)/ gain from discontinued operations	(18.6)	(18.3)	(248.7)	9.5	(2.8)	(24.3)	(4.5)	(2.5)	(276.1)	(34.1)	122.7
Net income / (loss)	$ 457.3	$ (386.8)	$ (162.1)	$ 419.0	$ 280.6	$ 452.8	$ 159.6	$ 410.4	$ 327.4	$ 1,303.4	$ 3,405.5
Schedule of Weighted Average Number of Shares
Basic (in shares)									770.1	590.4	586.7
Effect of dilutive shares:
Share based awards to employees (in shares)									6.1	2.7	4.6
Diluted (in shares)									776.2	593.1	591.3
Earning per ordinary share - basic
Earnings from continuing operations (in USD per share)	$ 0.53	$ (0.41)	$ 0.12	$ 0.69	$ 0.48	$ 0.81	$ 0.28	$ 0.70	$ 0.780	$ 2.27	$ 5.596
(Loss)/gain from discontinued operations (in USD per share)	(0.02)	(0.02)	(0.36)	0.02	(0.01)	(0.04)	(0.01)	0.00	(0.350)	(0.058)	0.209
Earnings per ordinary share - basic (in USD per share)	0.51	(0.43)	(0.24)	0.71	0.47	0.77	0.27	0.70	0.43	2.21	5.81
Earnings per ordinary share - diluted
Earnings from continuing operations (in USD per share)	0.52	(0.41)	0.12	0.69	0.48	0.80	0.28	0.70	0.770	2.255	5.552
(Loss)/gain from discontinued operations (in USD per share)	(0.02)	(0.02)	(0.36)	0.02	(0.01)	(0.04)	(0.01)	0.00	(0.350)	(0.058)	0.208
Earnings per ordinary share - diluted (in USD per share)	$ 0.50	$ (0.43)	$ (0.24)	$ 0.71	$ 0.47	$ 0.76	$ 0.27	$ 0.70	$ 0.42	$ 2.20	$ 5.76