Basis of Presentation and Consolidation (Schedule of Changes in Accumulated Other Comprehensive Income by Component) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ (43,277)	[1]		$ (45,379)	[1]
Other comprehensive income before reclassifications	1,337	[1]		3,524	[1]
Amounts reclassified from accumulated other comprehensive income	(85)	[1]		(170)	[1]
Other comprehensive income (loss)	1,252	[1]	(373)	3,354	[1]	92
Ending balance	(42,025)	[1]	(42,998)	(42,025)	[1]	(42,998)
Losses on Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(872)	[1]		(902)	[1]
Other comprehensive income before reclassifications	108	[1]		138	[1]
Amounts reclassified from accumulated other comprehensive income	0	[1]		0	[1]
Other comprehensive income (loss)	108	[1]		138	[1]
Ending balance	(764)	[1]		(764)	[1]
Investment in Debt Securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	2,872	[1]		2,569	[1]
Other comprehensive income before reclassifications	0	[1]		303	[1]
Amounts reclassified from accumulated other comprehensive income	0	[1]		0	[1]
Other comprehensive income (loss)	0	[1]		303	[1]
Ending balance	2,872	[1]		2,872	[1]
Defined Benefit Plan Items
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(45,277)	[1]		(47,046)	[1]
Other comprehensive income before reclassifications	1,229	[1]		3,083	[1]
Amounts reclassified from accumulated other comprehensive income	(85)	[1]		(170)	[1]
Other comprehensive income (loss)	1,144	[1]		2,913	[1]
Ending balance	$ (44,133)	[1]		$ (44,133)	[1]

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