Balance Sheet Account Detail (Fair Value Measurements) (Details) (Recurring, USD $)	Dec. 31, 2014	Dec. 31, 2013
Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$ 84,500,000	$ 84,900,000
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	26,798,000	95,152,000
Contingently issuable common stock	14,600,000	60,900,000
Corporate bonds | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	26,798,000	95,152,000
Contingently issuable common stock	0
Corporate bonds | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Contingently issuable common stock	0
Corporate bonds | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Contingently issuable common stock	$ 14,600,000	$ 60,900,000