Income Taxes - Reconciliation of Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of statutory tax to effective tax
Federal statutory tax rate	$ 35,655	$ 9,499
REIT and other non-taxable income	(36,425)	(8,964)
State income taxes	(139)	(95)
Federal benefit of state tax deduction	49	33
Other	(123)	(379)
Total	$ (983)	$ 94
Reconciliation of statutory tax rate to effective tax rate
Federal statutory tax rate (as a percent)	35.00%	35.00%
REIT and other non-taxable income (as a percent)	(35.80%)	(33.00%)
State income taxes (as a percent)	(0.10%)	(0.40%)
Federal benefit of state tax deduction (as a percent)		0.10%
Other (as a percent)	(0.10%)	(1.40%)
Effective tax rate (as a percent)	(1.00%)	0.30%