Fair Value Measurements (Assets Measured At Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	$ 47,343		$ 47,343		$ 23,763
Asset Impairment Charges	(11,350)	0	(11,350)	0
Fixed Income Mutual Fund
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	2,492		2,492		2,485
U.S. Government And Agency Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	2,914		2,914		2,233
Corporate Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	28,059		28,059		14,159
Other Fixed Income Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	437		437		361
International Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	12,894		12,894		3,048
Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	547		547		1,477
Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	2,492		2,492		2,485
Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Fixed Income Mutual Fund
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	2,492		2,492		2,485
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	44,851		44,851		21,278
Significant Other Observable Inputs (Level 2) | U.S. Government And Agency Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	2,914		2,914		2,233
Significant Other Observable Inputs (Level 2) | Corporate Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	28,059		28,059		14,159	[1]
Significant Other Observable Inputs (Level 2) | Corporate Obligations | Line of Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments					4,500
Significant Other Observable Inputs (Level 2) | Other Fixed Income Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	437		437		361
Significant Other Observable Inputs (Level 2) | International Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	12,894		12,894		3,048
Significant Other Observable Inputs (Level 2) | Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Short-term investments	$ 547		$ 547		$ 1,477

[1] Included in this amount is a corporate obligation of $4.5 million used to collateralize the Company's line of credit with Bank of America, and was included in the line item "Restricted cash and investments," a component of current assets, on the consolidated balance sheet as of December 31, 2013. Pursuant to an amendment to the loan agreement with Bank of America, effective May 19, 2014, the line of credit is no longer secured by cash or investment collateral. See Note 7, Credit Facilities, for further details.