Investment Securities - Company's Investments' Gross Unrealized Losses and Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 17,859	$ 5,540
Less Than 12 Months, Unrealized Losses	122	5
12 Months or Longer, Fair Value	1,916	6,582
12 Months or Longer, Unrealized Losses	30	72
Total, Fair Value	19,775	12,122
Total, Unrealized Losses	152	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	17,859	5,540
Less Than 12 Months, Unrealized Losses	122	5
12 Months or Longer, Fair Value	44	4,563
12 Months or Longer, Unrealized Losses	1	38
Total, Fair Value	17,903	10,103
Total, Unrealized Losses	123	43
Ginnie Mae Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	1,872	2,019
12 Months or Longer, Unrealized Losses	29	34
Total, Fair Value	1,872	2,019
Total, Unrealized Losses	$ 29	$ 34