Accumulated Other Comprehensive Income (''AOCI'') (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Changes in AOCI
Balance at the beginning of the period, net of taxes	$ 1,417	$ 1,187	$ 2,681	$ 955
Other comprehensive (loss) before reclassification, net of taxes	(6,139)	1,954	(7,418)	2,161
Amounts reclassified from other comprehensive income (loss), net of taxes	32	22	47	47
Other comprehensive income (loss)	(6,107)	1,976	(7,371)	2,208
Balance at the end of the period, net of taxes	(4,690)	3,163	(4,690)	3,163
Unrealized Gains (Losses) on Available-for-Sale Securities and I/O Strips
Changes in AOCI
Balance at the beginning of the period, net of taxes	6,614	6,410	7,887	6,210
Other comprehensive (loss) before reclassification, net of taxes	(6,116)	1,971	(7,371)	2,186
Amounts reclassified from other comprehensive income (loss), net of taxes	(4)	(19)	(22)	(34)
Other comprehensive income (loss)	(6,120)	1,952	(7,393)	2,152
Balance at the end of the period, net of taxes	494	8,362	494	8,362
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	489		497
Amounts reclassified from other comprehensive income (loss), net of taxes	(8)		(16)
Other comprehensive income (loss)	(8)		(16)
Balance at the end of the period, net of taxes	481		481
Defined Benefit Pension Plan Items
Changes in AOCI
Balance at the beginning of the period, net of taxes	(5,686)	(5,223)	(5,703)	(5,255)
Other comprehensive (loss) before reclassification, net of taxes	(23)	(17)	(47)	(25)
Amounts reclassified from other comprehensive income (loss), net of taxes	44	41	85	81
Other comprehensive income (loss)	21	24	38	56
Balance at the end of the period, net of taxes	$ (5,665)	$ (5,199)	$ (5,665)	$ (5,199)