Fair Value Measurements and Investments - Schedule of Reconciliation of Debt Securities (Detail) - Debt Security [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 17,820	$ 16,050	$ 12,220
Gains (losses) recorded for the period
Recognized in other expense, net	0	0	(5,585)
Recognized in other comprehensive income (loss)	(2,593)	1,770	9,415
Change in classification of debt security to held to maturity	(15,227)	0	0
Issuance of Warrant as consideration for extension	491	0	0
Impairment of Warrant	(491)	0	0
Ending balance	$ 0	$ 17,820	$ 16,050