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Stock Based Compensation - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense (gain)	$ 2,600		$ 2,300		$ 4,800	$ 4,500
Unrecognized stock-based compensation cost	8,800				$ 8,800
Unrecognized share-based compensation expense, weighted-average recognition period (in years)					1 year 5 months 15 days
Common stock issuance ESPP Plan	928	$ 796	$ 653	$ 419
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 5,000				$ 5,000
Unrecognized share-based compensation expense, weighted-average recognition period (in years)					1 year 5 months 23 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan, discount rate (as a percent)					15.00%
Common stock issuance ESPP Plan (in shares)	41,058		37,255		75,388	73,287
Common stock issuance ESPP Plan	$ 200		$ 200		$ 400	$ 300