Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value of Financial Instruments
Total securities available-for-sale	$ 392,439	$ 401,690
Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	392,439	401,690
Residential mortgage-backed securities
Fair Value of Financial Instruments
Total securities available-for-sale	296,964	310,534
Residential mortgage-backed securities | Recurring basis
Fair Value of Financial Instruments
Percentage of debt securities comprising available-for-sale portfolio	76.00%	77.00%
Available-for-sale residential mortgage-backed securities portfolio which are GSE securities (as a percent)	98.00%	98.00%
Residential MBS GSE issuance REMICs
Fair Value of Financial Instruments
Total securities available-for-sale	275,586	286,074
Residential MBS GSE issuance REMICs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	275,586	286,074
Non-GSE issuance REMICs and CMOs
Fair Value of Financial Instruments
Total securities available-for-sale	6,473	7,572
Non-GSE issuance REMICs and CMOs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	6,473	7,572
GSE pass-through certificates
Fair Value of Financial Instruments
Total securities available-for-sale	14,905	16,888
GSE pass-through certificates | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	14,905	16,888
Obligations of GSEs
Fair Value of Financial Instruments
Total securities available-for-sale	95,472	91,153
Obligations of GSEs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	95,472	91,153
Percentage of debt securities comprising available-for-sale portfolio	24.00%	23.00%
Fannie Mae stock
Fair Value of Financial Instruments
Total securities available-for-sale	3	3
Fannie Mae stock | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	3	3
Level 1 | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	3	3
Level 1 | Fannie Mae stock | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	3	3
Level 2 | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	392,436	401,687
Level 2 | Residential MBS GSE issuance REMICs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	275,586	286,074
Level 2 | Non-GSE issuance REMICs and CMOs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	6,473	7,572
Level 2 | GSE pass-through certificates | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	14,905	16,888
Level 2 | Obligations of GSEs | Recurring basis
Fair Value of Financial Instruments
Total securities available-for-sale	$ 95,472	$ 91,153