Derivative Instruments (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	May 22, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative assets	$ 2,581.1		$ 2,581.1			$ 3,176.1
Carrying value	45,320.2		45,320.2			42,315.9
Cross-Currency and Interest Rate Derivative Contracts [Member]
Derivative [Line Items]
Gain (loss) in changes in the credit risk valuation adjustments associated with our cross-currency and interest rate derivative contracts	72.2	$ (14.3)	145.3	$ 7.1
Derivative assets	$ 1,999.5		$ 1,999.5			2,606.5
Lionsgate Forward [Member]
Derivative [Line Items]
Number of common stock shares owned (in shares)	2.5		2.5
Counterparty Credit Risk [Member]
Derivative [Line Items]
Derivative assets	$ 1,131.4		$ 1,131.4
Equity Contract [Member]
Derivative [Line Items]
Derivative assets	$ 556.6		$ 556.6		$ 51.0	$ 524.0
Securities borrowed					117.4
Sumitomo Collar Loan [Member] | Equity Contract [Member]
Derivative [Line Items]
Carrying value					$ 169.9