Commitments and Contingent Liabilities - Reserve for Unfunded Loan Commitments and for Repurchase of Previously Sold Loans (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Reserve for unfunded commitment losses
Reserve for unfunded commitment losses beginning balance	$ 1,956	$ 2,557	$ 4,664
Provision for unfunded commitments	2,708	17	(2,107)
Ending reserve for unfunded commitment losses	4,664	2,574	2,557
Reserve for repurchased loans
Reserve for repurchased loans beginning balance	2,600	1,338	2,600
Charge off	0	(172)	(1,176)
Recovery	0	74	27
Provision for repurchased loans	0	(212)	(113)
Ending reserve for repurchased loans	$ 2,600	$ 1,028	$ 1,338