Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ (21,181)	[1]	$ (45,379)	[1]
Other comprehensive income before reclassifications	(2,891)	[1]	2,187	[1]
Amounts reclassified from accumulated other comprehensive income (loss)	(85)	[1]	(85)	[1]
Other comprehensive income (loss)	(2,976)	[1]	2,102	[1]
Ending balance	(24,157)	[1]	(43,277)	[1]
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(637)	[1]	(902)	[1]
Other comprehensive income before reclassifications	69	[1]	30	[1]
Amounts reclassified from accumulated other comprehensive income (loss)	0	[1]	0	[1]
Other comprehensive income (loss)	69	[1]	30	[1]
Ending balance	(568)	[1]	(872)	[1]
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	7,861	[1]	2,569	[1]
Other comprehensive income before reclassifications	(3,232)	[1]	303	[1]
Amounts reclassified from accumulated other comprehensive income (loss)	0	[1]	0	[1]
Other comprehensive income (loss)	(3,232)	[1]	303	[1]
Ending balance	4,629	[1]	2,872	[1]
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(28,405)	[1]	(47,046)	[1]
Other comprehensive income before reclassifications	272	[1]	1,854	[1]
Amounts reclassified from accumulated other comprehensive income (loss)	(85)	[1]	(85)	[1]
Other comprehensive income (loss)	187	[1]	1,769	[1]
Ending balance	$ (28,218)	[1]	$ (45,277)	[1]

[1] All amounts are net of tax. Amounts in parentheses indicates debits