Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	$ (16,507)
Unrealized gains (losses)	752
Amounts reclassified from accumulated other comprehensive income	739
Balance at March 31, 2013	(15,016)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	2,244
Unrealized gains (losses)	(204)
Amounts reclassified from accumulated other comprehensive income	(550)
Balance at March 31, 2013	1,490
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(18,286)
Unrealized gains (losses)
Amounts reclassified from accumulated other comprehensive income	1,251
Balance at March 31, 2013	(17,035)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(465)
Unrealized gains (losses)	956
Amounts reclassified from accumulated other comprehensive income	38
Balance at March 31, 2013	$ 529