Share-Based Compensation - Components of Share-Based Compensation Expense by Type of Award (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 4,226	$ 2,822	$ 2,416
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	741	881	678
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	3,473	1,897	1,630
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	755	1,155	2,076
Change in Estimate of Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ (743)	$ (1,111)	$ (1,968)