Investments and Fair Value Instruments - Summary of Changes in Fair Value and Other Adjustments of Liabilities (Detail) - Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 4,987	$ 16,936
Initial recognition	9,631
Change in fair value and other adjustments	(9,155)	(6,570)
Exercise of warrants		(5,659)
ISI acquisition contingent consideration		280
Ending Balance	5,463	4,987
Common Stock Warrant Liability [Member] | Purchase Agreement [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	661	4,579
Change in fair value and other adjustments	(654)	(2,277)
Exercise of warrants		(1,641)
Ending Balance	7	661
Common Stock Warrant Liability [Member] | June 2018 Offering [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance		5,444
Change in fair value and other adjustments		(1,426)
Exercise of warrants		(4,018)
Common Stock Warrant Liability [Member] | June 2019 Offering [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	832	1,993
Change in fair value and other adjustments	(662)	(1,161)
Ending Balance	170	832
Common Stock Warrant Liability [Member] | September 2019 Offering [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,214	2,920
Change in fair value and other adjustments	(991)	(1,706)
Ending Balance	223	1,214
Common Stock Warrant Liability [Member] | January 2021 Offering [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Initial recognition	9,631
Change in fair value and other adjustments	(6,638)
Ending Balance	2,993
Contingent Liabilities [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	2,280	2,000
Change in fair value and other adjustments	(210)
ISI acquisition contingent consideration		280
Ending Balance	$ 2,070	$ 2,280