Share Capital - Narrative (Details) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended	0 Months Ended		12 Months Ended	6 Months Ended
	Feb. 21, 2014 2014 Repurchase Authorization	Jun. 30, 2014 2014 Repurchase Authorization	Jun. 30, 2014 2014 Repurchase Authorization	Feb. 21, 2014 2013 Repurchase Authorization	Feb. 22, 2013 2013 Repurchase Authorization	Dec. 31, 2013 2013 Repurchase Authorization	Jun. 30, 2014 Stock options	Jun. 30, 2014 Restricted Stock [Member]	Jun. 30, 2014 Restricted stock units	Jun. 30, 2014 Performance units	Jun. 30, 2014 Minimum [Member]	Jun. 30, 2014 Minimum [Member] Performance units	Jun. 30, 2014 Maximum [Member]	Jun. 30, 2014 Maximum [Member] Performance units
Shareholders Equity Disclosure [Line Items]
Stock Repurchase Program, Authorized Amount	$ 1,000,000,000				$ 850,000,000
Stock Repurchased and Retired During Period, Shares		5,500,000	11,300,000
Stock Repurchased and Retired During Period, Value		175,000,000	350,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount			717,600,000	200,000,000		275,000,000
Weighted Average Grant Date Fair Value Per Stock Option							$ 8.60
Number of Stock Options Granted During the Period							1,000,000	42,444
Number of Awards Granted During the Period									1,800,000	600,000
Aggregate Grant Date Fair Value of Award								$ 1,400,000	$ 54,300,000	$ 16,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period									3 years	3 years	3 years		4 years
Share Based Compensation Arrangement Performance Units Maximum Share Payout Number										1,100,000
Performance Units Final Payout Percentage Of Grant Amount												0.00%		200.00%