Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 28,778	$ 24,857	$ 88,090	$ 66,417
Other comprehensive (loss) income, net of tax
Unrealized (losses) gains on securities	(928)	(881)	13,079	(33,220)
Pension and other postretirement benefits	455	825	1,367	2,477
Other comprehensive (loss) income, net of tax	(473)	(56)	14,446	(30,743)
Comprehensive income	$ 28,305	$ 24,801	$ 102,536	$ 35,674