Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Changes in AOCI
Balance at the beginning of the period, net of taxes	$ 2,681	$ 955
Other comprehensive (loss) before reclassification, net of taxes	(1,279)	208
Amounts reclassified from other comprehensive income (loss), net of taxes	15	25
Other comprehensive income (loss)	(1,264)	233
Balance at the end of the period, net of taxes	1,417	1,188
Unrealized Gains on Available-for-Sale Securities and I/O Strips
Changes in AOCI
Balance at the beginning of the period, net of taxes	7,887	6,210
Other comprehensive (loss) before reclassification, net of taxes	(1,255)	216
Amounts reclassified from other comprehensive income (loss), net of taxes	(18)	(16)
Other comprehensive income (loss)	(1,273)	200
Balance at the end of the period, net of taxes	6,614	6,410
Unamortized Unrealized Gain on Available-for-Sale Securities Reclassified to Held-to-Maturity
Changes in AOCI
Balance at the beginning of the period, net of taxes	497
Amounts reclassified from other comprehensive income (loss), net of taxes	(8)
Other comprehensive income (loss)	(8)
Balance at the end of the period, net of taxes	489
Defined Benefit Pension Plan Items
Changes in AOCI
Balance at the beginning of the period, net of taxes	(5,703)	(5,255)
Other comprehensive (loss) before reclassification, net of taxes	(24)	(8)
Amounts reclassified from other comprehensive income (loss), net of taxes	41	41
Other comprehensive income (loss)	17	33
Balance at the end of the period, net of taxes	$ (5,686)	$ (5,222)