Net Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Earnings Per Share
Net earnings (loss) attributable to common stockholders	$ 708.5	$ 406.5
Basic earnings per common share:
Weighted average common shares outstanding	54.8	62.3
Net earnings attributable to common stockholders basic (in dollars per share)	$ 12.94	$ 6.53
Diluted earnings per common share:
Weighted average common shares outstanding	54.8	62.3
Dilutive common shares - stock options	0.1	0.5
Diluted weighted average shares outstanding	54.9	62.8
Net earnings attributable to common stockholders diluted (in dollars per share)	$ 12.90	$ 6.47