Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 30,868	$ 20,755	$ 59,312	$ 41,560
Other comprehensive (loss) income, net of tax
Unrealized (losses) gains on securities	6,564	(27,039)	14,007	(32,339)
Pension and other postretirement benefits	456	826	912	1,652
Other comprehensive (loss) income, net of tax	7,020	(26,213)	14,919	(30,687)
Comprehensive income	$ 37,888	$ (5,458)	$ 74,231	$ 10,873