Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2014	$ 3,241
Unrealized gains (losses)	789
Amounts reclassified from AOCI	3,031
Balance at June 30, 2015	7,061
Derivative Instruments [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2014	2,550
Unrealized gains (losses)	3,234
Amounts reclassified from AOCI	(2,051)
Balance at June 30, 2015	3,733
Pension, Postretirement and Other Postemployment Benefits [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2014	2,860
Unrealized gains (losses)	0
Amounts reclassified from AOCI	2,411
Balance at June 30, 2015	5,271
Available-for-Sale Securities [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Balance at December 31, 2014	(2,169)
Unrealized gains (losses)	(2,445)
Amounts reclassified from AOCI	2,671
Balance at June 30, 2015	$ (1,943)