Accumulated Other Comprehensive Income (Loss) Reclassifications Out of AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (24,244)	$ 48,603
Other comprehensive income (loss) before reclassification	20,627	(9,931)
Amounts reclassified from accumulated other comprehensive income (loss)	(47)	790
Income tax (expense) benefit	(7,913)	3,529
Net other comprehensive income (loss) during period	12,667	(5,612)
Ending Balance	(11,577)	42,991
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(11,396)	86,109
Other comprehensive income (loss) before reclassification	20,627	(9,931)
Amounts reclassified from accumulated other comprehensive income (loss)	(378)	(300)
Income tax (expense) benefit	(7,786)	3,950
Net other comprehensive income (loss) during period	12,463	(6,281)
Ending Balance	1,067	79,828
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(12,848)	(37,506)
Other comprehensive income (loss) before reclassification	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	331	1,090
Income tax (expense) benefit	(127)	(421)
Net other comprehensive income (loss) during period	204	669
Ending Balance	$ (12,644)	$ (36,837)