Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net income	$ 21,393	$ 20,044
Other comprehensive income (loss), before tax:
Change in net unrealized gains (losses) during period	14,351	(5,717)
Reclassification adjustment for net gains included in income	(71)	(8)
Defined benefit post-retirement benefits plans:
Change in net actuarial loss	35	35
Other comprehensive income (loss), before tax	14,315	(5,690)
Deferred tax benefit (expense) related to other comprehensive income	(5,633)	2,239
Other comprehensive income (loss), net of tax	8,682	(3,451)
Comprehensive income, net of tax	$ 30,075	$ 16,593