Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financial assets measured and recognized at fair value on a recurring basis
Total	$ 111,561	$ 95,557
Certificates of Deposit [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	310	310
Money Market Funds [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	111,251	95,247
Level 1 [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	111,251	95,247
Level 1 [Member] | Certificates of Deposit [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total
Level 1 [Member] | Money Market Funds [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	111,251	95,247
Level 2 [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	310	310
Level 2 [Member] | Certificates of Deposit [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total	310	310
Level 2 [Member] | Money Market Funds [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total
Level 3 [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total
Level 3 [Member] | Certificates of Deposit [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total
Level 3 [Member] | Money Market Funds [Member]
Financial assets measured and recognized at fair value on a recurring basis
Total