SHARE-BASED COMPENSATION - Stock option plan (Detail) - Stock option - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of shares
Options outstanding, beginning of year (in shares)	623,122	1,006,144
Options granted (in shares)	0	0	0
Options exercised (in shares)	(39,500)	(360,776)
Options forfeited (in shares)	(3,268)	(16,362)
Options expired (in shares)	(112,865)	(5,884)
Options outstanding, end of year (in shares)	467,489	623,122	1,006,144
Options exercisable (in shares)	463,590	586,081
Options vested and expected to vest (in shares)	467,060	619,032
Weighted average exercise price
Options outstanding, beginning of year (in dollars per share)	$ 20.83	$ 19.48
Options granted (in dollars per share)	0	0
Options exercised (in dollars per share)	17.90	16.46
Options forfeited (in dollars per share)	28.89	30.45
Options expired (in dollars per share)	19.26	31.30
Options outstanding, end of year (in dollars per share)	21.40	20.83	$ 19.48
Options exercisable (in dollars per share)	21.31	20.40
Options vested and expected to vest (in dollars per share)	$ 21.39	$ 20.79
Options outstanding, end of year (in years)	4 years 1 month 6 days	4 years 9 months 18 days
Options exercisable (in years)	4 years 1 month 6 days	4 years 7 months 6 days
Options vested and expected to vest (in years)	4 years 1 month 6 days	4 years 9 months 18 days