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, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Significant Unobservable Inputs (Level 3) | Residential Mortgage Loan Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning	$ 43	$ 240
Issuances	87	103
Settlements	(43)	(240)
Balance at ending	$ 87	$ 103