Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 18,009	$ 7,649
Other comprehensive income (loss), net of tax
Unrealized net holding gains (losses) arising during the period (pre-tax amounts of $8,623 and ($1,752))	5,208	(1,058)
Reclassification adjustment for net gains related to securities available for sale included in net income (pre-tax amounts of $7 and $1,145)	(4)	(691)
Pension and other benefits:
Amortization of prior service cost and actuarial gains (pre-tax amounts of $19 and $826)	11	503
Total other comprehensive income (loss)	5,215	(1,246)
Comprehensive income	$ 23,224	$ 6,403