Investment Securities - Company's Investments' Gross Unrealized Losses and Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 8,955	$ 5,540
Less Than 12 Months, Unrealized Losses	45	5
12 Months or Longer, Fair Value	1,858	6,582
12 Months or Longer, Unrealized Losses	12	72
Total, Fair Value	10,813	12,122
Total, Unrealized Losses	57	77
Ginnie Mae and GSE Mortgage-Backed Pass-Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	8,955	5,540
Less Than 12 Months, Unrealized Losses	45	5
12 Months or Longer, Fair Value	42	4,563
12 Months or Longer, Unrealized Losses	1	38
Total, Fair Value	8,997	10,103
Total, Unrealized Losses	46	43
Ginnie Mae Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	1,816	2,019
12 Months or Longer, Unrealized Losses	11	34
Total, Fair Value	1,816	2,019
Total, Unrealized Losses	$ 11	$ 34