Schedule of Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Change in net unrealized Gain during period:
Change in net unrealized gain during period, before tax amount	$ (5,717)	$ 755
Change in net unrealized gain during period, tax expense (benefit)	(2,250)	296
Change in net unrealized gain during period, net of tax amount	(3,467)	459
Reclassification adjustment for gains included in net income:
Reclassification adjustment for gains included in net income, before tax amount	(8)	(31)
Reclassification adjustment for gains included in net income, tax expense (benefit)	(3)	(12)
Reclassification adjustment for gains included in net income, net of tax amount	(5)	(19)
Change in net actuarial loss:
Change in net actuarial loss, before tax amount	35	33
Change in net actuarial loss, tax expense (benefit)	14	13
Change in net actuarial loss, net of tax amount	21	20
Other comprehensive income (loss):
Other comprehensive income (loss), before tax	(5,690)	757
Total other comprehensive income, tax expense (benefit)	(2,239)	297
Total other comprehensive income, net of tax amount	$ (3,451)	$ 460