Schedule of Available for Sale Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	$ 16,184	$ 39,652
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and Cash Equivalents, Fair Value Disclosure	16,184	39,652
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	100,676	87,998
Available-for-sale Securities, Gross Unrealized Gain1	22	34
Available-for-sale Securities, Gross Unrealized Loss1	(51)	(8)
AFS Securities, Fair Value Disclosure	100,647	88,024
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash, Cash Equiv. And S-T Investments, Amortized Cost	116,860	127,650
Cash, Cash Equiv. And S-T Investments, Gross Unrealized Gains	22	34
Cash, Cash Equiv. And S-T Investments, Gross Unrealized Losses	(51)	(8)
Cash, Cash Equiv. And S-T Investments, Fair Value Disclosure	116,831	127,676
Demand deposits and other cash
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	9,409	15,451
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and Cash Equivalents, Fair Value Disclosure	9,409	15,451
Money market funds
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	6,775	22,991
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and Cash Equivalents, Fair Value Disclosure	6,775	22,991
Commercial Paper in CE
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost		150
Cash And Cash Equivalents, Gross Unrealized Gains		0
Cash And Cash Equivalents, Gross Unrealized Losses		0
Cash and Cash Equivalents, Fair Value Disclosure		150
Corporate Debt Securities
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost		1,060
Cash And Cash Equivalents, Gross Unrealized Gains		0
Cash And Cash Equivalents, Gross Unrealized Losses		0
Cash and Cash Equivalents, Fair Value Disclosure		1,060
Prepaid Expenses and Other Current Assets
Schedule of available for sale securities [Line Items]
Restricted cash	40	305
Commercial paper in STI
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	1,599	750
Available-for-sale Securities, Gross Unrealized Gain1	0	0
Available-for-sale Securities, Gross Unrealized Loss1	0	0
AFS Securities, Fair Value Disclosure	1,599	750
U.S. government agency securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	8,502	11,275
Available-for-sale Securities, Gross Unrealized Gain1	3	5
Available-for-sale Securities, Gross Unrealized Loss1	0	(1)
AFS Securities, Fair Value Disclosure	8,505	11,279
U.S. Treasury securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	3,551	5,233
Available-for-sale Securities, Gross Unrealized Gain1	3	2
Available-for-sale Securities, Gross Unrealized Loss1	0	0
AFS Securities, Fair Value Disclosure	3,554	5,235
Municipal debt securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	3,944	4,758
Available-for-sale Securities, Gross Unrealized Gain1	4	7
Available-for-sale Securities, Gross Unrealized Loss1	0	0
AFS Securities, Fair Value Disclosure	3,948	4,765
Corporate Debt Securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	83,080	65,982
Available-for-sale Securities, Gross Unrealized Gain1	12	20
Available-for-sale Securities, Gross Unrealized Loss1	(51)	(7)
AFS Securities, Fair Value Disclosure	$ 83,041	$ 65,995