Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets:
Investments in marketable securities	$ 261,985	$ 264,443
Derivatives	17,082	19,954
Total assets	279,067
Liabilities, Fair Value Disclosure, Recurring	56
Derivative Liability	56	12
Level 1 [Member]
Assets:
Investments in marketable securities	12,918
Derivatives	12,144
Total assets	25,062
Liabilities, Fair Value Disclosure, Recurring
Level 2 [Member]
Assets:
Investments in marketable securities	249,067
Derivatives	392
Total assets	249,459
Liabilities, Fair Value Disclosure, Recurring	49
Level 3 [Member]
Assets:
Investments in marketable securities
Derivatives	4,546
Total assets	4,546
Liabilities, Fair Value Disclosure, Recurring	$ 7