Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (32,266)	$ (60,204)	$ (13,709)
Other comprehensive income (loss) before reclassifications	(28,530)	23,245	(35,760)
Amounts reclassified from accumulated other comprehensive loss	12,247	4,693	(10,735)
Net current-period other comprehensive loss, net of tax	(16,283)	27,938	(46,495)
Ending Balance	(48,549)	(32,266)	(60,204)
Available for Sale and Transferred Securities) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	42,741	15,967	17,529
Other comprehensive income (loss) before reclassifications	(49,572)	28,950	923
Amounts reclassified from accumulated other comprehensive loss	4,214	(2,176)	(2,485)
Net current-period other comprehensive loss, net of tax	(45,358)	26,774	(1,562)
Ending Balance	(2,617)	42,741	15,967
Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(27,902)	(28,884)	(5,889)
Other comprehensive income (loss) before reclassifications	3,744	(3,243)	(14,447)
Amounts reclassified from accumulated other comprehensive loss	5,952	4,225	(8,548)
Net current-period other comprehensive loss, net of tax	9,696	982	(22,995)
Ending Balance	(18,206)	(27,902)	(28,884)
Defined Benefit Pension and Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(47,105)	(47,287)	(25,349)
Other comprehensive income (loss) before reclassifications	17,298	(2,462)	(22,236)
Amounts reclassified from accumulated other comprehensive loss	2,081	2,644	298
Net current-period other comprehensive loss, net of tax	19,379	182	(21,938)
Ending Balance	$ (27,726)	$ (47,105)	$ (47,287)