Income Taxes - Schedule of Income (Loss) Before Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount
Federal income tax at statutory rate									$ 21,445	$ 19,121	$ 43,357
State income tax, net of federal benefit									5,249	4,067	3,835
Tax-exempt interest, net of disallowance									(385)	(360)	(381)
Bank-owned life insurance									(1,677)	(1,547)	(2,675)
Tax credits									(1,266)	(444)	0
Equity-based compensation									132	(547)	(10,741)
Non-deductible executive compensation									440	230	654
Unrecorded basis difference in foreign subsidiaries									(144)	343	4,527
Enactment of federal tax reform										(21)	5,505
Other									(1,001)	(1,483)	961
Effective income tax rate	$ 7,451	$ 8,020	$ 2,491	$ 4,831	$ 5,109	$ 28	$ 6,820	$ 7,402	$ 22,793	$ 19,359	$ 45,042
% of pretax income
Federal income tax at statutory rate									21.00%	21.00%	35.00%
State income tax, net of federal benefit									5.14%	4.47%	3.10%
Tax-exempt interest, net of disallowance									(0.38%)	(0.40%)	(0.31%)
Bank-owned life insurance									(1.64%)	(1.70%)	(2.16%)
Tax credits									(1.24%)	(0.49%)	0.00%
Equity-based compensation									0.13%	(0.60%)	(8.67%)
Non-deductible executive compensation									0.43%	0.25%	0.53%
Unrecorded basis difference in foreign subsidiaries									(0.14%)	0.38%	3.65%
Enactment of federal tax reform										(0.0002)	0.0444
Other									(0.98%)	(1.63%)	0.78%
Effective income tax rate									22.32%	21.26%	36.36%