Derivative Instruments - Realized and Unrealized Gain (Loss) on Derivatives Not Designated as Hedging Instruments (Details) - Derivatives not designated as hedging instruments: - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Unrealized (Loss) Gain	$ (41,217)	$ 29,278	$ 946
Realized Gain (Loss)	129,509	(622)	(7,030)
Total Gain (Loss)	88,292	28,656	(6,084)
Contingent redemption features - Series A Preferred Stock
Derivative [Line Items]
Unrealized (Loss) Gain	(42,140)	33,294	1,735
Realized Gain (Loss)	140,320	0	0
Total Gain (Loss)	98,180	33,294	1,735
Cross currency and interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	750	(4,191)	(873)
Realized Gain (Loss)	(10,811)	(622)	(6,811)
Total Gain (Loss)	(10,061)	(4,813)	(7,684)
Interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	173	175	84
Realized Gain (Loss)	0	0	(219)
Total Gain (Loss)	$ 173	$ 175	$ (135)