Derivative Instruments - Realized and Unrealized Gain (Loss) on Derivatives Not Designated as Hedging Instruments (Details) - Derivatives not designated as hedging instruments: - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Unrealized (Loss) Gain	$ (19,765)	$ (3,962)	$ 19,621	$ (1,548)
Realized (Loss) Gain	(165)	4,478	(434)	(6,687)
Total (Loss) Gain	(19,930)	516	19,187	(8,235)
Contingent redemption features - Series A Preferred Stock
Derivative [Line Items]
Unrealized (Loss) Gain	(19,974)	0	19,468	0
Total (Loss) Gain	(19,974)	0	19,468	0
Cross currency and interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	151	(3,979)	24	(1,514)
Realized (Loss) Gain	(165)	4,539	(434)	(6,530)
Total (Loss) Gain	(14)	560	(410)	(8,044)
Interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	58	17	129	(34)
Realized (Loss) Gain	0	(61)	0	(157)
Total (Loss) Gain	$ 58	$ (44)	$ 129	$ (191)