Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (27,705)	$ (21,539)
Other comprehensive income (loss):
Unrealized (gains) losses from change in fair value based on instrument specific credit risk	1,266
Total other comprehensive income (loss)	1,266
Comprehensive income (loss) before allocation to noncontrolling interests	(26,439)	(21,539)
(Income) loss allocated to noncontrolling interests		(20)
Comprehensive income (loss) allocable to common shares	$ (26,439)	$ (21,559)