Financial Instruments and Fair Value Measurements (Carrying Amounts and Fair Value) (Details) (USD $) | 9 Months Ended | 12 Months Ended | | |
In Thousands, unless otherwise specified | Sep. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Dec. 31, 2012 |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $43,133 | $44,644 | ' | ' |
Cash | 40,682 | 14,092 | ' | ' |
Money market funds | 3,177 | 16,431 | ' | ' |
Cash and Cash Equivalents, at Carrying Value | 43,859 | 33,462 | 21,651 | 44,114 |
Available-for-sale Securities, Amortized Cost Basis | 108,369 | 102,644 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax | 65 | 38 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax | -102 | -72 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss | -102 | -72 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 43,133 | 44,644 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss | 102 | 72 | ' | ' |
Available-for-sale Securities | 108,332 | 102,610 | ' | ' |
Municipal Bonds [Member] | ' | ' | ' | ' |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | ' | 552 | ' | ' |
Available-for-sale Securities, Amortized Cost Basis | 3,410 | 3,827 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax | 8 | 5 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax | 0 | -2 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss | ' | -2 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | ' | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss | ' | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | ' | 552 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss | ' | 2 | ' | ' |
Available-for-sale Securities | 3,418 | 3,830 | ' | ' |
US Government and Government Agencies and Authorities [Member] | ' | ' | ' | ' |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 26,509 | 24,975 | ' | ' |
Available-for-sale Securities, Amortized Cost Basis | 61,115 | 57,102 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax | 29 | 15 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax | -62 | -31 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss | -62 | -31 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 26,509 | 24,975 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss | 62 | 31 | ' | ' |
Available-for-sale Securities | 61,082 | 57,086 | ' | ' |
Certificates of Deposit [Member] | ' | ' | ' | ' |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 4,803 | 12,714 | ' | ' |
Available-for-sale Securities, Amortized Cost Basis | 14,372 | 14,945 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax | 12 | 1 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax | -15 | -26 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss | -15 | -26 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 4,803 | 12,714 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss | 15 | 26 | ' | ' |
Available-for-sale Securities | 14,369 | 14,920 | ' | ' |
Corporate Note Securities [Member] | ' | ' | ' | ' |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 11,821 | 6,403 | ' | ' |
Available-for-sale Securities, Amortized Cost Basis | 29,472 | 26,770 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax | 16 | 17 | ' | ' |
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax | -25 | -13 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss | -25 | -13 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss | 0 | 0 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 11,821 | 6,403 | ' | ' |
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss | 25 | 13 | ' | ' |
Available-for-sale Securities | 29,463 | 26,774 | ' | ' |
US Government Agencies Debt Securities [Member] | ' | ' | ' | ' |
Schedule of Available-for-sale Securities [Line Items] | ' | ' | ' | ' |
Available-for-sale Securities, Amortized Cost Basis | ' | 2,939 | ' | ' |
Available-for-sale Securities | ' | $2,939 | ' | ' |