Income Taxes - Dividends Paid Deduction (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends Paid Deduction [Line Items]
Distributions	$ 141,172	$ 116,725	$ 192,271
Less: non-dividend distributions	(17,630)	(38,497)	0
Total dividends paid deduction attributable to earnings and profits	$ 123,542	$ 78,228	$ 192,271
Qualified business income deduction	20.00%	20.00%
Liabilities recorded for uncertain income tax positions	$ 0	$ 0
7.00% Series A cumulative redeemable preferred stock
Dividends Paid Deduction [Line Items]
Ordinary dividends (per share)	$ 0	$ 0	$ 1.62
Capital gain distributions (per share)	0	0	0.07
Total distributions per share	0	0	1.69
Class A common stock
Dividends Paid Deduction [Line Items]
Ordinary dividends (per share)	0.58	0.36	0.76
Non-dividend distributions (per share)	0.08	0.17	0
Capital gain distributions (per share)	0	0	0.03
Total distributions per share	$ 0.66	$ 0.53	$ 0.79