Schedule of Comprehensive Income (Loss) (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
Change in net unrealized Gain during period:
Change in net unrealized gain during period, before tax amount	$ (35,625)	$ (1,864)	$ (41,342)	$ (1,107)
Change in net unrealized gain during period, tax expense (benefit)	(14,018)	(733)	(16,268)	(436)
Change in net unrealized gain during period, net of tax amount	(21,607)	(1,131)	(25,074)	(671)
Reclassification adjustment for gains included in net income:
Reclassification adjustment for gains included in net income, before tax amount	12	(198)	4	(229)
Reclassification adjustment for gains included in net income, tax expense (benefit)	5	(78)	2	(90)
Reclassification adjustment for gains included in net income, net of tax amount	7	(120)	2	(139)
Change in net actuarial loss:
Change in net actuarial loss, before tax amount	35	35	70	68
Change in net actuarial loss, tax expense (benefit)	14	14	28	27
Change in net actuarial loss, net of tax amount	21	21	42	41
Other comprehensive income (loss):
Other comprehensive income (loss), before tax	(35,578)	(2,027)	(41,268)	(1,268)
Total other comprehensive income, tax expense (benefit)	(13,999)	(797)	(16,238)	(499)
Total other comprehensive income, net of tax amount	$ (21,579)	$ (1,230)	$ (25,030)	$ (769)