Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (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
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 1,531
Other comprehensive income (loss)	(4,356)	870	(4,505)	1,202
Ending balance	(2,974)	434	(2,974)	434
Available-for-Sale Securities Without Other-Than-Temporary Impairments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	8,524	7,036	9,451	7,202
Unrealized gains/losses arising during the period	(9,143)	1,493	(10,054)	1,918
Reclassifications from accumulated other comprehensive income	(1,378)	(1)	(1,394)	(592)
Other comprehensive income (loss)	(10,521)	1,492	(11,448)	1,326
Ending balance	(1,997)	8,528	(1,997)	8,528
Available-for-Sale Securities With Other-Than-Temporary Impairments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,152)	(2,265)	(2,162)	(2,318)
Unrealized gains/losses arising during the period	114	(21)	124	32
Reclassifications from accumulated other comprehensive income	2,038	4	2,038	4
Other comprehensive income (loss)	2,152	(17)	2,162	36
Ending balance	0	(2,282)	0	(2,282)
Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,396)	(1,728)	(2,484)	(1,834)
Unrealized gains/losses arising during the period	660	(772)	591	(812)
Reclassifications from accumulated other comprehensive income	171	151	328	297
Other comprehensive income (loss)	831	(621)	919	(515)
Ending balance	(1,565)	(2,349)	(1,565)	(2,349)
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,773)	(3,738)	(2,364)	(4,272)
Unrealized gains/losses arising during the period	0	0	0	0
Reclassifications from accumulated other comprehensive income	591	534	1,182	1,068
Other comprehensive income (loss)	591	534	1,182	1,068
Ending balance	$ (1,182)	$ (3,204)	$ (1,182)	$ (3,204)