Derivative Instruments (Narrative) (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative [Line Items]
Derivative assets	$ 2,547.8		$ 2,496.7
Cross-currency and interest rate derivative contracts
Derivative [Line Items]
Gain (loss) in changes in the credit risk valuation adjustments associated with our cross-currency and interest rate derivative contracts	(58.1)	$ 37.7
Derivative assets	1,778.0		$ 1,742.8
Counterparty Credit Risk
Derivative [Line Items]
Derivative assets	$ 604.8
Ordinary shares | Lionsgate Loan
Derivative [Line Items]
Number of common stock shares owned (in shares)	1,250
Nonvoting Common Stock | Lionsgate Loan
Derivative [Line Items]
Number of common stock shares owned (in shares)	1,250