Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 23,812	$ 16,155	$ 65,361	$ 41,379
Other comprehensive income (loss), before tax:
Change in net unrealized gains (losses) during period	1,794	931	(39,547)	(175)
Reclassification adjustment for net gains included in income	(30)	(66)	(26)	(295)
Defined benefit post-retirement benefits plans:
Change in net actuarial loss	33	35	102	102
Other comprehensive income (loss), before tax	1,797	900	(39,471)	(368)
Deferred tax benefit (expense) related to other comprehensive income	(707)	(354)	15,532	145
Other comprehensive income (loss), net of tax	1,090	546	(23,939)	(223)
Comprehensive income, net of tax	$ 24,902	$ 16,701	$ 41,422	$ 41,156