Benefit Plans (Schedule Of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 1,754	$ 1,755	$ 1,754	$ 2,079	$ 5,263	$ 6,236
Interest cost	6,454	6,454	6,454	7,411	19,362	22,227
Expected return on assets	(10,873)	$ (10,874)	$ (10,873)	(11,204)	(32,620)	(33,616)
Amortization of prior service cost	1,296			1,217	3,888	3,650
Amortization of actuarial loss	3,474			3,470	10,422	10,420
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0			(206)	0	(206)
Net periodic benefit cost	$ 2,105			$ 3,179	$ 6,315	$ 9,123