Summary of Significant Accounting Policies - Summary of Revision of Prior Period Financial Statements (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement:
Earnings before income tax	$ 81,556	$ 59,151	$ 58,119
Income tax expense	21,866	10,285	16,220
Net income	$ 59,690	$ 48,866	$ 41,899
Basic EPS	$ 1.83	$ 1.48	$ 1.17
Diluted EPS	$ 1.81	$ 1.47	$ 1.16
Balance Sheet:
Deferred income tax asset - long term	$ 73,912	$ 69,096
Total non-current assets		364,969
Total assets	1,022,839	738,832
Accumulated other comprehensive (loss) income	(14,982)	(42,355)	$ (39,500)	$ (20,444)
Accumulated earnings	472,782	413,092
Total liabilities and shareholders’ equity	$ 1,022,839	738,832
As Reported
Income Statement:
Earnings before income tax		59,151
Income tax expense		21,645
Net income		$ 37,506
Basic EPS		$ 1.13
Diluted EPS		$ 1.13
Balance Sheet:
Deferred income tax asset - long term		$ 57,650
Total non-current assets		353,523
Total assets		727,386
Accumulated other comprehensive (loss) income		(42,441)
Accumulated earnings		401,732
Total liabilities and shareholders’ equity		727,386
Adjustment
Income Statement:
Income tax expense		(11,360)
Net income		$ 11,360
Basic EPS		$ 0.35
Diluted EPS		$ 0.34
Balance Sheet:
Deferred income tax asset - long term		$ 11,446
Total non-current assets		11,446
Total assets		11,446
Accumulated other comprehensive (loss) income		86
Accumulated earnings		11,360
Total liabilities and shareholders’ equity		$ 11,446