Employee Compensation and Benefit Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan Description of 401 K Plan
Employee Benefits Disclosure [Line Items]
Maximum percentage of pre-tax income employees are allowed to contribute towards 401(k) plan	75.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount	$ 18,000	$ 18,000	$ 17,500
Maximum percentage of employer matching contributions towards 401(k) plan	5.00%
Employee Stock Ownership Plan (ESOP), Plan
Employee Benefits Disclosure [Line Items]
Maximum percentage of employee's eligible pay earned in the fiscal year contributed by the company in cash or common stock towards ESOP	10.00%
ESOP contributions vesting period	5 years
Employee Home Ownership Plan
Employee Benefits Disclosure [Line Items]
Fixed-rate mortgage loan term, minimum	5 years
Fixed-rate mortgage loan term, maximum	7 years
Amortization period	30 years
Maximum loan amount percentage lesser of purchase price or the appraised value	80.00%
Mortgage loans rate	2.00%
Number of days loan rate locked	30 days
Loans Receivable, Description of Variable Rate Basis	The loan rate shall not be less than the greater of either the jumbo conforming market rate (corresponding to the maturity of the loan) or the monthly Applicable Federal Rate for medium-term loans as published by the Internal Revenue Service. The loan rate will be fixed at the time of approval and locked in for 30 days.
Deferred Compensation Plan
Employee Benefits Disclosure [Line Items]
Maximum percentage of base salary that may be deferred under the DC Plan	50.00%
Maximum percentage of eligible bonus payment that may be deferred under the DC Plan	100.00%
Maximum deferral term under the DC Plan	12 months
Deferrals under the DC Plan	$ 4,400,000	3,700,000	3,900,000
Deferred compensation arrangement with individual employee mandatory retention incentive deferrals	2,800,000
DC Plan investment gains	$ 2,400,000	$ 100,000	$ 1,400,000