Schedule of Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Change in net unrealized Gain during period:
Change in net unrealized gain during period, before tax amount	$ 14,351	$ (5,717)
Change in net unrealized gain during period, tax expense (benefit)	5,647	(2,250)
Change in net unrealized gain during period, net of tax amount	8,704	(3,467)
Reclassification adjustment for gains included in net income:
Reclassification adjustment for gains included in net income, before tax amount	(71)	(8)
Reclassification adjustment for gains included in net income, tax expense (benefit)	(28)	(3)
Reclassification adjustment for gains included in net income, net of tax amount	(43)	(5)
Change in net actuarial loss:
Change in net actuarial loss, before tax amount	35	35
Change in net actuarial loss, tax expense (benefit)	14	14
Change in net actuarial loss, net of tax amount	21	21
Other comprehensive income (loss):
Other comprehensive income (loss), before tax	14,315	(5,690)
Total other comprehensive income, tax expense (benefit)	5,633	(2,239)
Total other comprehensive income, net of tax amount	$ 8,682	$ (3,451)