Consolidated Statements of Comprehensive Income (unaudited) (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 (unaudited) [Abstract]
Net income	$ 10,912	$ 19,257	$ 56,561	$ 43,822
Other comprehensive (loss) income, net of tax
Unrealized net holding (losses) gains arising during the period (pre-tax amounts of ($3,693), ($6,927), $13,199 and ($33,391))	(2,124)	(4,184)	8,075	(20,167)
Reclassification adjustment for net gains related to securities available for sale included in net income (pre-tax amounts of $38, $329, $58 and $1,413)	(23)	(197)	(35)	(848)
Amortization of unrealized net gains and losses related to the reclassification of available for sale investment securities to held to maturity (pre-tax amounts of $99, $-, $99 and $-)	(59)	0	(59)	0
Pension and other benefits:
Amortization of prior service cost and actuarial gains (pre-tax amounts of $19, $709, $57 and $2,244)	11	426	34	1,354
Increase in unrecognized actuarial gains (pre-tax amounts of $-, $4,036, $-, and $4,036)	0	2,421	0	2,421
Total other comprehensive (loss) income	(2,195)	(1,534)	8,015	(17,240)
Comprehensive income	$ 8,717	$ 17,723	$ 64,576	$ 26,582