Financial Instruments (Fair Value Of Investments) (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Marketable investment securities available for sale in an unrealized loss position
In Loss Position for Less Than 12 Months, Fair Value	$ 90,327	$ 74,407
In Loss Position for Less Than 12 Months, Gross Unrealized Losses	78	56
In Loss Position for More Than 12 Months, Fair Value	0	5,732
In Loss Position for More Than 12 Months, Gross Unrealized Losses	0	4
Total, Fair Value	90,327	80,139
Total, Gross Unrealized Losses	78	60
Corporate
Marketable investment securities available for sale in an unrealized loss position
In Loss Position for Less Than 12 Months, Fair Value	90,327	74,407
In Loss Position for Less Than 12 Months, Gross Unrealized Losses	78	56
In Loss Position for More Than 12 Months, Fair Value	0	5,732
In Loss Position for More Than 12 Months, Gross Unrealized Losses	0	4
Total, Fair Value	90,327	80,139
Total, Gross Unrealized Losses	78	60
Government agency
Marketable investment securities available for sale in an unrealized loss position
In Loss Position for Less Than 12 Months, Fair Value	0	0
In Loss Position for Less Than 12 Months, Gross Unrealized Losses	0	0
In Loss Position for More Than 12 Months, Fair Value	0	0
In Loss Position for More Than 12 Months, Gross Unrealized Losses	0	0
Total, Fair Value	0	0
Total, Gross Unrealized Losses	$ 0	$ 0