Net Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Net earnings available to common stockholders	$ 787.4	$ 163.3	$ 848.4	$ 315.3	[1]
Distributed and allocated undistributed net loss to non-vested restricted stockholders	(5.0)	(1.2)	(5.3)	(2.2)
Distributed and allocated undistributed net earnings to common stockholders	782.4	162.1	843.1	313.1
Distributed net (loss) earnings - dividends paid to common stockholders	(30.1)	(31.3)	(91.5)	(88.0)
Allocation of undistributed net earnings to common stockholders	$ 752.3	$ 130.8	$ 751.6	$ 225.1
Denominator
Weighted average number of common shares outstanding - basic	186.9	194.1	190.9	195.0
Basic net earnings per common share:
Distributed net earnings to common stockholders (in dollars per share)	$ 0.16	$ 0.16	$ 0.48	$ 0.45
Allocated undistributed net earnings to common stockholders (in dollars per share)	4.03	0.68	3.94	1.15
Net earnings per common share - basic (in dollars per share)	$ 4.19	$ 0.84	$ 4.42	$ 1.60
Numerator
Distributed and allocated undistributed net earnings to common stockholders	$ 782.4	$ 162.1	$ 843.1	$ 313.1
Add: Allocated undistributed net earnings to unvested restricted stockholders	4.8	1.1	4.8	1.7
Less: Undistributed net earnings (loss) reallocated to non-vested restricted stockholders	(4.8)	(1.1)	(4.8)	(1.7)
Net earnings available to common stockholders - diluted	$ 782.4	$ 162.1	$ 843.1	$ 313.1
Denominator
Weighted average number of common shares outstanding - basic	186.9	194.1	190.9	195.0
Effect of contingently issuable shares (in shares)	0.7	1.0	0.7	0.9
Effect of unvested restricted stock units (in shares)	0.7	0.9	0.7	0.9
Weighted average number of common shares outstanding - diluted under two-class	188.3	196.0	192.3	196.8
Effect of unvested restricted stock - participating security (in shares)	0.6	0.7	0.6	0.7
Weighted average number of common shares outstanding - diluted under treasury stock	188.9	196.7	192.9	197.5
Diluted net earnings per common share (in dollars per share)	$ 4.15	$ 0.83	$ 4.37	$ 1.59

[1] Due to changes in the accounting treatment of a factoring agreement the Company reclassified amounts from cash and cash equivalents to other receivables of $8.7 million as of September 30, 2016. This reclassification resulted in an increase in cash provided by operating activities of $2.0 million for the nine months ended September 30, 2016.