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Share Capital - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	May 13, 2016	Aug. 06, 2015
Shareholders Equity Disclosure [Line Items]
Stock Repurchased and Retired During Period, Shares	6,600,000	26,200,000
Stock Repurchased and Retired During Period, Value	$ 221.7	$ 905.1
Minimum
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Maximum
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Stock options
Shareholders Equity Disclosure [Line Items]
Weighted Average Grant Date Fair Value Per Stock Option		$ 5.99
Number of Stock Options Granted During the Period		2,200,000
Restricted stock
Shareholders Equity Disclosure [Line Items]
Number of Awards Granted During the Period		48,466
Aggregate Grant Date Fair Value of Award		$ 1.7
Restricted stock units
Shareholders Equity Disclosure [Line Items]
Number of Awards Granted During the Period		1,100,000
Aggregate Grant Date Fair Value of Award		$ 38.3
Restricted stock units \| Three Year Option
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Restricted stock units \| Four Year Option
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Liability-classed cash units
Shareholders Equity Disclosure [Line Items]
Number of Awards Granted During the Period		1,800,000
Aggregate Grant Date Fair Value of Award		$ 61.7
Liability-classed cash units \| Three Year Option
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Liability-classed cash units \| Four Year Option
Shareholders Equity Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Performance Shares
Shareholders Equity Disclosure [Line Items]
Number of Awards Granted During the Period		700,000
Share Based Compensation Arrangement Performance Units Maximum Share Payout Number		1,500,000
Aggregate Grant Date Fair Value of Award		$ 25.6
Performance Shares \| Minimum
Shareholders Equity Disclosure [Line Items]
Performance Units Final Payout Percentage Of Grant Amount		0.00%
Performance Shares \| Maximum
Shareholders Equity Disclosure [Line Items]
Performance Units Final Payout Percentage Of Grant Amount		200.00%
August 2015 Program
Shareholders Equity Disclosure [Line Items]
Stock Repurchase Program, Authorized Amount				$ 1,000.0
Stock Repurchased and Retired During Period, Shares	0	14,200,000
Stock Repurchased and Retired During Period, Value	$ 0.0	$ 499.3
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 204.1
May 2016 Program
Shareholders Equity Disclosure [Line Items]
Stock Repurchase Program, Authorized Amount			$ 1,000.0
Stock Repurchased and Retired During Period, Shares	6,600,000	12,000,000
Stock Repurchased and Retired During Period, Value	$ 221.7	$ 405.8
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 594.1	$ 594.1