Disclosures About Fair Value of Financial Instruments - Statement of Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) - Significant Unobservable Inputs (Level 3) - Residential Mortgage Loan Commitments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning	$ 71	$ 54	$ 43	$ 240
Issuances	70	35	228	192
Settlements	(71)	(54)	(201)	(397)
Balance at ending	$ 70	$ 35	$ 70	$ 35