Income Taxes - Reconciliation of Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2017
Reconciliation of statutory tax to effective tax
Federal statutory tax rate	$ 31,849	$ 28,556	$ 16,520	$ 44,692
REIT and other non-taxable income	(26,923)	666	(17,009)	(42,172)
State income taxes	1,619	(26,013)	(160)	660
Federal benefit of state tax deduction	(340)	(140)	34	(139)
Net operating loss carryback rate differential	(3,717)		(3,717)
Intra-entity transfer	(3,781)		(3,781)
Other	(5)	464	86	826
Total income tax provision	$ (1,298)	$ 3,533	$ (8,027)	$ 3,867
Reconciliation of statutory tax rate to effective tax rate
Federal statutory tax rate (as a percent)	21.00%	21.00%	21.00%	21.00%	35.00%
REIT and other non-taxable income (as a percent)	(17.80%)	(19.10%)	(21.60%)	(19.80%)
State income taxes (as a percent)	1.10%	0.50%	(0.20%)	0.30%
Federal benefit of state tax deduction (as a percent)	(0.20%)	(0.10%)		(0.10%)
Net operating loss carryback rate differential (as a pecent)	(2.50%)		(4.70%)
Intra-entity transfer	(2.50%)		(4.80%)
Other (as a percent)		0.30%	0.10%	0.40%
Effective tax rate (as a percent)	(0.90%)	2.60%	(10.20%)	1.80%