Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	[1]	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. federal income taxes (including foreign withholding taxes):
Current federal income taxes										$ 117.8	$ 8.0	$ 46.9
Deferred federal income taxes										46.9	130.7	25.2
Total federal income taxes										164.7	138.7	72.1
State and local income taxes:
Current state and local income taxes										15.1	9.7	(14.7)
Deferred state and local income taxes										13.0	23.8	24.7
Total state and local income taxes										28.1	33.5	10.0
Foreign income taxes:
Current foreign income taxes										100.4	115.3	79.6
Deferred foreign income taxes										(10.4)	(71.0)	19.5
Total foreign income taxes										90.0	44.3	99.1
Total provision for income taxes	$ 145.4	$ 61.1	$ 77.7	$ (1.4)	$ 87.9		$ 65.0	$ 65.3	$ (1.7)	$ 282.8	$ 216.5	$ 181.2

[1] The three months ended December 31, 2014 included a tax benefit of $67.6 due to the net reversal of valuation allowances on deferred tax assets in Continental Europe.