Stockholder's Equity - Schedule of Shares Repurchased (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 03, 2020	Nov. 06, 2019	May 06, 2019	Dec. 12, 2018
Equity [Line Items]
Shares repurchased during the period	$ 28,921,000	$ 66,186,000	$ 25,276,000
December Two Thousand Twenty Share Repurchase Program [Member]
Equity [Line Items]
Shares repurchased (in shares)	45,705	0
Shares repurchased during the period	$ 593,000
Shares repurchased during period (in dollars per share)	$ 12.98
December Two Thousand Twenty Share Repurchase Program [Member] \| Maximum [Member]
Equity [Line Items]
Amount of stock repurchase plan authorized				$ 20,000,000
November Two Thousand Nineteen Share Repurchase Program [Member]
Equity [Line Items]
Shares repurchased (in shares)	1,565,078	403,142
Shares repurchased during the period	$ 40,000,000
Shares repurchased during period (in dollars per share)	$ 20.32
November Two Thousand Nineteen Share Repurchase Program [Member] \| Maximum [Member]
Equity [Line Items]
Amount of stock repurchase plan authorized					$ 40,000,000
May Two Thousand Nineteen Share Repurchase Program [Member]
Equity [Line Items]
Shares repurchased (in shares)	0	1,466,575
Shares repurchased during the period	$ 40,000,000
Shares repurchased during period (in dollars per share)	$ 27.27
May Two Thousand Nineteen Share Repurchase Program [Member] \| Maximum [Member]
Equity [Line Items]
Amount of stock repurchase plan authorized						$ 40,000,000
December Two Thousand Eighteen Share Repurchase Program [Member]
Equity [Line Items]
Shares repurchased (in shares)	0	468,108
Shares repurchased during the period	$ 14,513,000
Shares repurchased during period (in dollars per share)	$ 31.00
December Two Thousand Eighteen Share Repurchase Program [Member] \| Maximum [Member]
Equity [Line Items]
Amount of stock repurchase plan authorized							$ 20,000,000