Other Comprehensive Income (Loss) (Components And Allocated Tax Effects Of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss) Components and Tax Effects [Line Items]
Net Unrealized Gain (Loss) on Marketable Securities before Taxes	$ 166	$ (165)	$ 171	$ (129)
Net unrealized gain (loss) on hedging instruments	(9,335)	(8,441)	(34,463)	112,957
Net change in pension and other post-retirement benefit obligation	0	422	0	333
Other comprehensive income (loss)	(9,169)	(8,184)	(34,292)	113,161
Less other comprehensive income attributable to noncontrolling interest	(158)	673	(477)	278
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Stockholders	(9,011)	(8,857)	(33,815)	112,883
Net Unrealized Gain (loss) on Marketable Securities, Tax	64	(64)	66	(50)
Net unrealized gain (loss) on hedging instruments, tax expense (benefit)	(3,552)	(3,527)	(13,154)	43,616
Net change in Pension and Other Postretirement Benefit Plans, Tax		163		128
Other comprehensive income, tax expense	(3,488)	(3,428)	(13,088)	43,694
Other Comprehensive Income (Loss), Tax, Portion Attributable to Stockholders	(3,488)	(3,428)	(13,088)	43,694
Net unrealized gain (loss) on marketable securities, after tax	102	(101)	105	(79)
Net unrealized gain (loss) on hedging instruments, after tax	(5,783)	(4,914)	(21,309)	69,341
Net Change in Pension and Other Post-retirement Benefit Obligations, After Tax		259		205
Other comprehensive income (loss), net of tax	(5,681)	(4,756)	(21,204)	69,467
Less other comprehensive income attributable to noncontrolling interest, after tax	(158)	673	(477)	278
Other Comprehensive Income (Loss) Portion Attributable to Stockholders	$ (5,523)	$ (5,429)	$ (20,727)	$ 69,189