Fair Value Measurements - Reconciliation of Level 3 Instruments (Detail) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	6 Months Ended
		Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Conversion of convertible senior notes	[1]		$ (9,473)
Redeemable Preferred Stock | Level 3 | Fair Value Measurements, Recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance				$ 5,247
Change in fair value				(2,083)
Ending Balance		$ 3,164	3,164	3,164
3.25% convertible senior notes due 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Conversion of convertible senior notes		(9,500)
3.25% convertible senior notes due 2023 | Level 3 | Fair Value Measurements, Recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance				50,753
Conversion of convertible senior notes				(9,473)
Change in fair value				52
Payment-in-kind interest				925
Ending Balance		$ 42,257	$ 42,257	$ 42,257

[1] After giving effect to a 1 for 10 reverse stock split effective July 9, 2020.