Reconciliation of Basic and Diluted Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Income (loss)	$ (57,023)	$ (116,884)	$ (84,728)	$ (138,423)
(Income) loss allocated to preferred shares	6,861	(8,817)	472	(17,343)
(Income) loss allocated to noncontrolling interests		(56)		(76)
Net income (loss) allocable to common shares	$ (50,162)	$ (125,757)	$ (84,256)	$ (155,842)
Weighted-average shares outstanding-Basic	91,991,289	91,453,415	91,933,302	91,377,508
Weighted-average shares outstanding—Diluted	91,991,289	91,453,415	91,933,302	91,377,508
Earnings (loss) per share-Basic:
Earnings (loss) per share-Basic	$ (0.55)	$ (1.38)	$ (0.92)	$ (1.71)
Earnings (loss) per share-Diluted:
Earnings (loss) per share-Diluted	$ (0.55)	$ (1.38)	$ (0.92)	$ (1.71)