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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative [Line Items]
Unrealized (Loss) Gain	$ (2,555)	$ (28,506)	$ 4,021	$ (37,679)
Realized Gain (Loss)	5,187	140,102	3,794	129,935
Total Gain (Loss)	2,632	111,596	7,815	92,256
Contingent redemption features - Series A Preferred Stock
Derivative [Line Items]
Unrealized (Loss) Gain	0	(28,607)	0	(42,140)
Realized Gain (Loss)	0	140,319	0	140,319
Total Gain (Loss)	0	111,712	0	98,179
Cross currency and interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	(2,555)	53	4,021	4,358
Realized Gain (Loss)	5,187	(217)	3,794	(10,384)
Total Gain (Loss)	2,632	(164)	7,815	(6,026)
Interest rate swaps
Derivative [Line Items]
Unrealized (Loss) Gain	0	48	0	103
Total Gain (Loss)	$ 0	$ 48	$ 0	$ 103