CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Pension and other post retirement obligations:
Amortization of actuarial losses included in net periodic pension cost, net of taxes of $392 and $359 in 2013 and 2012, respectively	$ 618	$ 566
Amortization of prior service cost included in net periodic pension cost, net of taxes of $12 and $94 in 2013 and 2012, respectively	(18)	(148)
Other comprehensive income related to pension and other post retirement obligations, net of taxes	600	418
Unrealized gains on securities:
Net unrealized holding losses arising during period, net of taxes of $7,098 and $2,424 in 2013 and 2012, respectively	(11,774)	(4,586)
Reclassification adjustment for gains included in net income, net of taxes of $17,844 and $0 in 2013 and 2012, respectively	(29,948)	0
Other comprehensive loss related to unrealized gain on available-for-sale securities, net of taxes	(41,722)	(4,586)
Other comprehensive (loss) income, net of tax	(41,122)	(4,168)
Net income	20,241	18,826
Comprehensive (loss) income	(20,881)	14,658
Accumulated Other Comprehensive Income By Component: [Abstract]
Unrealized loss for pension and other postretirement obligations	(44,252)		(45,232)
Tax effect	17,067		17,447
Net unrealized loss for pension and other postretirement obligations	(27,185)		(27,785)
Unrealized gain on available-for-sale securities	64,793		131,456
Tax effect	(24,396)		(49,337)
Net unrealized gain on available-for-sale securities	40,397		82,119
Accumulated other comprehensive income	$ 13,212		$ 54,334