Schedule of Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Change in net unrealized Gain during period:
Change in net unrealized gain during period, before tax amount	$ (1,864)	$ 21,000	$ (1,107)	$ 21,419
Change in net unrealized gain during period, tax expense (benefit)	(733)	8,263	(436)	8,428
Change in net unrealized gain during period, net of tax amount	(1,131)	12,737	(671)	12,991
Reclassification adjustment for gains included in net income:
Reclassification adjustment for gains included in net income, before tax amount	(198)	(16)	(229)	(18)
Reclassification adjustment for gains included in net income, tax expense (benefit)	(78)	(6)	(90)	(7)
Reclassification adjustment for gains included in net income, net of tax amount	(120)	(10)	(139)	(11)
Change in net actuarial loss:
Change in net actuarial loss, before tax amount	35	35	68	69
Change in net actuarial loss, tax expense (benefit)	14	14	27	27
Change in net actuarial loss, net of tax amount	21	21	41	42
Other comprehensive income (loss):
Other comprehensive income, before tax	(2,027)	21,019	(1,268)	21,470
Total other comprehensive income, tax expense (benefit)	(797)	8,271	(499)	8,448
Total other comprehensive income, net of tax amount	$ (1,230)	$ 12,748	$ (769)	$ 13,022