Federal Home Loan Bank Advances and Other Borrowings (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Federal Home Loan Bank Advances and Other Borrowings
Aggregate principal balance of real estate loans used to collateralize FHLB advances	$ 343,800,000
FHLB stock used to collateralize FHLB advances	9,228,000	10,456,000
Activities in advances from the FHLB
Average balance outstanding	9,154,000	6,630,000
Maximum amount outstanding at any month-end during the year	87,000,000	35,000,000
Balance outstanding at end of year	87,000,000
Weighted average interest rate during the year (as a percent)	0.28%	0.80%
Additional available advances	150,300,000
Federal Home Loan Bank Advances and Other Borrowings
Estimated fair value of MBS used to secure outstanding borrowings	45,300,000
Credit facilities | Citigroup
Federal Home Loan Bank Advances and Other Borrowings
Borrowings	18,500,000	18,500,000
Activities in other borrowings
Balance outstanding at end of year	18,500,000	18,500,000
Credit facilities | Barclays Bank
Federal Home Loan Bank Advances and Other Borrowings
Borrowings	10,000,000	10,000,000
Activities in other borrowings
Balance outstanding at end of year	10,000,000	10,000,000
Reverse repurchase facility | Union Bank
Federal Home Loan Bank Advances and Other Borrowings
Unused facility	50,000,000	20,000,000
Unsecured lines of credit
Federal Home Loan Bank Advances and Other Borrowings
Unused facility	59,000,000
Number of correspondent banks	7
Other Borrowings
Federal Home Loan Bank Advances and Other Borrowings
Borrowings	28,500,000	28,500,000
Activities in other borrowings
Average balance outstanding	28,500,000	28,500,000
Maximum amount outstanding at any month-end during the year	28,500,000	28,500,000
Balance outstanding at end of year	28,500,000	28,500,000
Weighted average interest rate during the year (as a percent)	3.31%	3.32%
Federal Reserve discount window
Federal Home Loan Bank Advances and Other Borrowings
Unused facility	$ 3,300,000