Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Other comprehensive income, net of tax
Unrealized net holding (losses) gains arising during the period (pre-tax amounts of ($24,712), ($309), (26,464) and $335)	(14,923)	(185)	(15,978)	201
Reclassification adjustment for net gains related to securities available for sale included in net income (pre-tax amounts of ($61), $97, $1,084 and $552)	37	(58)	(650)	(331)
Pension and other benefits:
Amortization of prior service cost and actuarial gains (pre-tax amounts of $710, $856, $1,536 and $1,713)	426	511	922	1,027
Total other comprehensive income	(14,460)	268	(15,706)	897
Comprehensive income	$ 2,456	$ 13,525	$ 8,859	$ 27,804