Accumulated Other Comprehensive Income (''AOCI'') (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in AOCI
Balance at the beginning of the period, net of taxes	$ (4,690)	$ 3,163	$ 2,681	$ 955
Other comprehensive income (loss) before reclassification, net of taxes	375	1,747	(7,043)	3,908
Amounts reclassified from other comprehensive income (loss), net of taxes	34	(95)	81	(48)
Other comprehensive income (loss)	409	1,652	(6,962)	3,860
Balance at the end of the period, net of taxes	(4,281)	4,815	(4,281)	4,815
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	494	8,362	7,887	6,210
Other comprehensive income (loss) before reclassification, net of taxes	391	1,766	(6,980)	3,952
Amounts reclassified from other comprehensive income (loss), net of taxes		(641)	(22)	(675)
Other comprehensive income (loss)	391	1,125	(7,002)	3,277
Balance at the end of the period, net of taxes	885	9,487	885	9,487
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	481		497
Amounts reclassified from other comprehensive income (loss), net of taxes	(8)	505	(24)	505
Other comprehensive income (loss)	(8)	505	(24)	505
Balance at the end of the period, net of taxes	473	505	473	505
Defined Benefit Pension Plan Items
Changes in AOCI
Balance at the beginning of the period, net of taxes	(5,665)	(5,199)	(5,703)	(5,255)
Other comprehensive income (loss) before reclassification, net of taxes	(16)	(19)	(63)	(44)
Amounts reclassified from other comprehensive income (loss), net of taxes	42	41	127	122
Other comprehensive income (loss)	26	22	64	78
Balance at the end of the period, net of taxes	$ (5,639)	$ (5,177)	$ (5,639)	$ (5,177)