Summary of Restricted Stock Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of shares
Number of shares, Unvested, beginning of year	1,083	1,254	1,519
Number of shares, Granted	293	437	514
Number of shares, Vested	(439)	(564)	(679)
Number of shares, Forfeited	(40)	(44)	(100)
Number of shares, Unvested, end of year	897	1,083	1,254
Weighted average grant date fair value, Unvested
Weighted average grant date fair value, Unvested, beginning of year	$ 41.31	$ 27.48	$ 21.24
Weighted average grant date fair value, Granted	101.04	57.46	34.05
Weighted average grant date fair value, Vested	35.58	23.48	18.89
Weighted average grant date fair value, Forfeited	57.39	35.86	24.82
Weighted average grant date fair value, Unvested, end of year	$ 62.69	$ 41.31	$ 27.48