Other Comprehensive Income (Loss) (Schedule Of Changes In AOCI Balances By Component (After-Tax)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	$ 1,420,227
Net other comprehensive income (loss)	1,150	$ (553)
Balance at the end of the quarter	1,440,331
Defined Benefit Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	(38,242)	(40,268)
Amounts reclassified from AOCI	247
Net other comprehensive income (loss)	247
Balance at the end of the quarter	(37,995)	(40,268)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	(4,603)	(1,389)
Other comprehensive income (loss) before reclassifications	930
Net other comprehensive income (loss)	930	(588)
Balance at the end of the quarter	(3,673)	(1,977)
Unrealized Gain (Loss) in Fair Value of Investments, net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	656	(110)
Other comprehensive income (loss) before reclassifications	8
Net other comprehensive income (loss)	8	(10)
Balance at the end of the quarter	664	(120)
Unrealized Gain (Loss) in Fair Value of Interest Rate Swap, net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	24	149
Other comprehensive income (loss) before reclassifications	(35)
Net other comprehensive income (loss)	(35)	45
Balance at the end of the quarter	(11)	194
Accumulated Other Comprehensive (Loss) Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of the quarter	(42,165)	(41,618)
Other comprehensive income (loss) before reclassifications	903
Amounts reclassified from AOCI	247
Net other comprehensive income (loss)	1,150	(553)
Balance at the end of the quarter	$ (41,015)	$ (42,171)