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Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2016	May 01, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized					12,925,000	15,425,000
Share-based compensation arrangement by share-based payment award, number of shares available for grant	4,972,432
Unrecognized stock option expense	$ 0
Unrecognized restricted stock unit expense	$ 7,000,000.0
Remaining weighted-average vesting period (years)	1 year 8 months 12 days
Share-based compensation arrangement by share-based payment award, compensation cost	$ 0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, expiration period		10 years	10 years	10 years