Summary of Significant Accounting Policies (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
(Increase) Decrease In Accumulated Other Comprehensive (Income) Loss [Roll Forward]
Beginning balance				$ 12,436	$ 4,202
Change excluding amounts reclassified from accumulated other comprehensive loss				(5,464)	(304)
Amounts reclassified from accumulated other comprehensive loss				(1,429)	(986)
Net other comprehensive (income) loss		$ (7,416)	$ (709)	(6,893)	(1,290)
Ending balance		5,543	2,912	5,543	2,912
(Gain) Loss On Investments [Member]
(Increase) Decrease In Accumulated Other Comprehensive (Income) Loss [Roll Forward]
Beginning balance				(656)	(340)
Change excluding amounts reclassified from accumulated other comprehensive loss				$ (76)	(252)
Amounts reclassified from accumulated other comprehensive loss					38	[1]
Net other comprehensive (income) loss				$ (76)	(214)
Ending balance		(732)	(554)	(732)	(554)
(Gain) Loss On Cash Flow Hedges [Member]
(Increase) Decrease In Accumulated Other Comprehensive (Income) Loss [Roll Forward]
Beginning balance				(3,416)	(1,233)
Change excluding amounts reclassified from accumulated other comprehensive loss				(5,388)	(52)
Amounts reclassified from accumulated other comprehensive loss	[2]			(709)	(876)
Net other comprehensive (income) loss				(6,097)	(928)
Ending balance		(9,513)	(2,161)	(9,513)	(2,161)
Defined Benefit Pension Plan [Member]
(Increase) Decrease In Accumulated Other Comprehensive (Income) Loss [Roll Forward]
Beginning balance				16,508	5,775
Amounts reclassified from accumulated other comprehensive loss	[3]			(720)	(148)
Net other comprehensive (income) loss				(720)	(148)
Ending balance		$ 15,788	$ 5,627	$ 15,788	$ 5,627

[1] This reclassification component is included in interest and other income.

[2] This reclassification component is included in interest expense (see Note 6 for additional information).

[3] This reclassification component is included in the computation of net periodic benefit cost (see Note 13 for additional information).