Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income	$ 21,505	$ 13,010	$ 41,549	$ 25,224
Other comprehensive income (loss), before tax:
Change in net unrealized gains (losses) during period	(35,625)	(1,864)	(41,342)	(1,107)
Reclassification adjustment for net gains included in income	12	(198)	4	(229)
Defined benefit post-retirement benefits plans:
Change in net actuarial loss	35	35	70	68
Other comprehensive income (loss), before tax	(35,578)	(2,027)	(41,268)	(1,268)
Deferred tax benefit (expense) related to other comprehensive income	13,999	797	16,238	499
Other comprehensive income (loss), net of tax	(21,579)	(1,230)	(25,030)	(769)
Comprehensive income, net of tax	$ (74)	$ 11,780	$ 16,519	$ 24,455