Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Taxes [Line Items]
Unrecognized tax benefits	$ 193.1		$ 193.1
Interest included in unrecognized tax benefits	43.5		43.5
State income taxes expense (benefit)	13.4	$ 0.7	14.2	$ 9.6
Foreign income taxes expense (benefit)	3.0	$ 0.0	0.8	$ 2.7
Jefferies [Member]
Income Taxes [Line Items]
Unrecognized tax benefits	$ 141.8		$ 141.8