Net Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net Earnings Per Share
Net earnings attributable to common stockholders	$ 312.6	$ 498.2	$ 1,021.1	$ 904.7
Basic earnings per common share:
Weighted average common shares outstanding	51.1	59.1	52.9	60.7
Net earnings attributable to common stockholders basic (in dollars per share)	$ 6.12	$ 8.43	$ 19.31	$ 14.91
Diluted earnings per common share:
Weighted average common shares outstanding	51.1	59.1	52.9	60.7
Dilutive common shares - stock options	0.1	0.4	0.2	0.4
Diluted weighted average shares outstanding	51.2	59.5	53.1	61.1
Net earnings attributable to common stockholders diluted (in dollars per share)	$ 6.10	$ 8.38	$ 19.24	$ 14.80