Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ (56,261)	$ (48,549)	$ (32,266)
Other comprehensive (loss) income before reclassifications	(29,043)	(10,191)	(28,530)
Amounts reclassified from accumulated other comprehensive income (loss)	7,198	2,479	12,247
Other comprehensive loss, net of tax	(21,845)	(7,712)	(16,283)
Ending Balance	(78,106)	(56,261)	(48,549)
Available For Sale and Transferred Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	16,421	(2,617)	42,741
Other comprehensive (loss) income before reclassifications	(22,512)	21,811	(49,572)
Amounts reclassified from accumulated other comprehensive income (loss)	(316)	(2,773)	4,214
Other comprehensive loss, net of tax	(22,828)	19,038	(45,358)
Ending Balance	(6,407)	16,421	(2,617)
Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(25,530)	(18,206)	(27,902)
Other comprehensive (loss) income before reclassifications	(3,136)	(12,506)	3,744
Amounts reclassified from accumulated other comprehensive income (loss)	5,686	5,182	5,952
Other comprehensive loss, net of tax	2,550	(7,324)	9,696
Ending Balance	(22,980)	(25,530)	(18,206)
Defined Benefit Pension and Postretirement Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(47,152)	(27,726)	(47,105)
Other comprehensive (loss) income before reclassifications	(3,395)	(19,496)	17,298
Amounts reclassified from accumulated other comprehensive income (loss)	1,828	70	2,081
Other comprehensive loss, net of tax	(1,567)	(19,426)	19,379
Ending Balance	$ (48,719)	$ (47,152)	$ (27,726)