Cash, Cash Equivalents and Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Cash equivalents and investments measured at fair value
Total	$ 51,863	$ 51,812
Level 1 [Member]
Cash equivalents and investments measured at fair value
Total	13,629	2,390
Level 2 [Member]
Cash equivalents and investments measured at fair value
Total	38,234	49,422
Level 3 [Member]
Cash equivalents and investments measured at fair value
Total	0	0
Money market funds [Member]
Cash equivalents and investments measured at fair value
Cash Equivalents	13,629	2,390
Money market funds [Member] \| Level 1 [Member]
Cash equivalents and investments measured at fair value
Cash Equivalents	13,629	2,390
Money market funds [Member] \| Level 2 [Member]
Cash equivalents and investments measured at fair value
Cash Equivalents	0	0
Money market funds [Member] \| Level 3 [Member]
Cash equivalents and investments measured at fair value
Cash Equivalents	0	0
U.S. government agency bonds [Member]
Cash equivalents and investments measured at fair value
Investments	16,019	18,256
U.S. government agency bonds [Member] \| Level 1 [Member]
Cash equivalents and investments measured at fair value
Investments	0	0
U.S. government agency bonds [Member] \| Level 2 [Member]
Cash equivalents and investments measured at fair value
Investments	16,019	18,256
U.S. government agency bonds [Member] \| Level 3 [Member]
Cash equivalents and investments measured at fair value
Investments	0	0
Municipal Bonds [Member]
Cash equivalents and investments measured at fair value
Investments	14,611	23,616
Municipal Bonds [Member] \| Level 1 [Member]
Cash equivalents and investments measured at fair value
Investments	0	0
Municipal Bonds [Member] \| Level 2 [Member]
Cash equivalents and investments measured at fair value
Investments	14,611	23,616
Municipal Bonds [Member] \| Level 3 [Member]
Cash equivalents and investments measured at fair value
Investments	0	0
Corporate debt securities [Member]
Cash equivalents and investments measured at fair value
Investments	7,604	7,550
Corporate debt securities [Member] \| Level 1 [Member]
Cash equivalents and investments measured at fair value
Investments	0	0
Corporate debt securities [Member] \| Level 2 [Member]
Cash equivalents and investments measured at fair value
Investments	7,604	7,550
Corporate debt securities [Member] \| Level 3 [Member]
Cash equivalents and investments measured at fair value
Investments	$ 0	$ 0

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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