Income Taxes Schedule of Effective Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
13. Income taxes [Abstract]
Statutory Accounting Practices, Statutory Net Income Amount									$ 8,236	$ 7,168	$ 8,181
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate									35.00%	35.00%	35.00%
Income Tax Reconciliation, Nondeductible Expense, Life Insurance									(444)	(375)	(465)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Life Insurance									(1.89%)	(1.83%)	(1.99%)
Income Tax Reconciliation, Nondeductible Expense									51	267	179
Effective Income Tax Rate Reconciliation, Nondeductible Expense									0.22%	1.30%	0.77%
Income Tax Reconciliation, Deductions, Dividends									0	105	301
Effective Income Tax Rate Reconciliation, Deductions, Dividends									0.00%	0.51%	1.29%
Income Tax Reconciliation, Tax Exempt Income									123	120	117
Effective Income Tax Rate Reconciliation, Tax Exempt Income									(0.52%)	(0.59%)	(0.50%)
Income Tax Reconciliation, State and Local Income Taxes									535	339	597
Effective Income Tax Rate Reconciliation, State and Local Income Taxes									2.27%	1.66%	2.55%
Income Tax Reconciliation, Nondeductible Expense, Amortization									0	0	(243)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization									0.00%	0.00%	(1.04%)
Income Tax Reconciliation, Prior Year Income Taxes									98	(506)	(647)
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes									0.42%	(2.47%)	(2.77%)
Income Tax Reconciliation, Other Adjustments									(58)	262	373
Effective Income Tax Rate Reconciliation, Other Adjustments									(0.25%)	1.28%	1.60%
Income taxes	$ 1,903	$ 2,397	$ 2,108	$ 1,887	$ 2,572	$ 2,209	$ 750	$ 1,609	$ 8,295	$ 7,140	$ 8,159
Effective Income Tax Rate, Continuing Operations									35.25%	34.86%	34.91%