Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2013	$ 37,692
Unrealized gains (losses)	(1,610)
Amounts reclassified from accumulated other comprehensive income	(1,020)
Balance at March 31, 2014	35,062
Derivative Instruments [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2013	565
Unrealized gains (losses)	47
Amounts reclassified from accumulated other comprehensive income	(194)
Balance at March 31, 2014	418
Pension, Postretirement and Other Postemployment Benefits [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2013	31,112
Unrealized gains (losses)	0
Amounts reclassified from accumulated other comprehensive income	(1,182)
Balance at March 31, 2014	29,930
Available-for-Sale Securities [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2013	6,015
Unrealized gains (losses)	(1,657)
Amounts reclassified from accumulated other comprehensive income	356
Balance at March 31, 2014	$ 4,714