Compensation - Activity Associated with Restricted Stock Units (Detail) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Units, Balance outstanding at beginning of period	4,478,000
Number of Units, Granted	4,433,000
Number of Units, Delivered units	(1,224,000)
Number of Units, Forfeited units	(161,000)
Number of Units, Balance outstanding at end of period	7,526,000	4,478,000
Weighted-Average Grant Date Fair Value, Balance outstanding at beginning of period	$ 5.25
Weighted-Average Grant Date Fair Value, Granted	3.73
Weighted-Average Grant Date Fair Value, Delivered units	5.79
Weighted-Average Grant Date Fair Value, Forfeited units	4.61
Weighted-Average Grant Date Fair Value, Balance outstanding at end of period	$ 4.28	$ 5.25
Fair Value, Balance outstanding at beginning of period	$ 23,516
Fair Value, Granted	16,536
Fair Value, Delivered units	(7,086)
Fair Value, Forfeited units	(744)
Fair Value, Balance outstanding at end of period	$ 32,222	$ 23,516
Weighted-Average Remaining Contractual Term (Years)	2 years 10 months 2 days	2 years 6 months