Derivative Financial Instruments - Net Gains (Losses) Related to Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) on derivative financial instruments	$ 1,801	$ (148)	$ (733)
Interest rate lock commitments
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) on derivative financial instruments	(688)	44	141
Unused commitments
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) on derivative financial instruments	26	0	(26)
Forward contracts to sell mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) on derivative financial instruments	$ 2,463	$ (192)	$ (848)