Preferred Shares - Summary of Preferred Share Balance (Detail) - Series A Preferred Stock [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Preferred Units [Line Items]
Issuance of Preferred Shares	$ 132,750	$ 132,750
Less: Issuance costs	(181)	(181)
Preferred Shares – carrying value	$ 132,569	$ 132,569