Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Fair value of asset measured on a recurring basis
Fixed income available-for-sale securities	$ 27,192		$ 42,987
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of asset measured on a recurring basis
Money market funds	12,008	[1]	5,254	[1]
Fixed income available-for-sale securities	0	[2],[3]	0	[2]
Total	12,008		5,254
Significant Other Observable Inputs (Level 2) [Member]
Fair value of asset measured on a recurring basis
Money market funds	0	[1]	0	[1]
Fixed income available-for-sale securities	27,192	[2],[3]	42,987	[2]
Total	27,192		42,987
Significant Unobservable Inputs (Level 3) [Member]
Fair value of asset measured on a recurring basis
Money market funds	0	[1]	0	[1]
Fixed income available-for-sale securities	0	[2],[3]	0	[2]
Total	0		0
Fair Value, Measurements, Recurring [Member]
Fair value of asset measured on a recurring basis
Money market funds	12,008	[1]	5,254	[1]
Fixed income available-for-sale securities	27,192	[2],[3]	42,987	[2]
Total	$ 39,200		$ 48,241

[1] Included in cash and cash equivalents in the Company’s condensed consolidated balance sheets

[2] Represents our portfolio of available for sale securities that is included in short-term investments in the Company’s condensed consolidated balance sheets

[3] Includes $6.3 million of available-for-sale securities that is included in restricted investments in the Company’s condensed consolidated balance sheets