Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expenses [Line Items]
Current income tax expense, Federal	$ 5,324	$ 10,481	$ 10,202
Current income tax expense, State	3,677	2,308	2,788
Current income tax expense, Total	9,001	12,789	12,990
Deferred income tax expense (benefit), Federal	(489)	(3,422)	1,088
Deferred income tax expense (benefit), State	(673)	(1,014)	(167)
Deferred income tax expense (benefit), Total	(1,162)	(4,436)	921
Income tax expense	$ 7,839	$ 8,353	$ 13,911