Other Expenses - Schedule of General and Administrative Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Professional services	$ 1,819	$ 1,662
Operating and other costs	693	1,451
Subtotal	2,512	3,113
Non-cash compensation expenses
Restricted class A common stock earned	7,960	8,553
Director stock-based compensation	125	125
Subtotal	8,085	8,678
Total general and administrative expenses	$ 10,597	$ 11,791