Income Taxes - Schedule of income tax benefit of TRSs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current	$ 185	$ (176)	$ 0
Deferred	(15,779)	(546)	3,223
Income tax (expense) benefit	$ (15,594)	$ (722)	$ 3,223