Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable - Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 261	$ 351	$ 303
Additions- Charges to (Recovery of) Costs and Expenses	141	175	124
Deductions- Write- offs/Costs Incurred	24	265	76
Balance at End of Year	378	261	351
Deferred Tax Assets - Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	51,589	45,626	26,920
Additions- Charges to (Recovery of) Costs and Expenses	13,471	8,279	21,042
Deductions- Write- offs/Costs Incurred	405	2,316	2,336
Balance at End of Year	$ 64,655	$ 51,589	$ 45,626