Fair Value Measurements (Assets Measured at Fair Value on a Recurring Basis ) (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Oct. 31, 2010	Dec. 31, 2010		Jun. 30, 2011
Cash equivalents		$ 139,010	[1]	$ 5,119	[1]
Short-term investments		490	[2],[3]	655	[2],[3]
Long-term investments		2,254	[4]
Total		141,754		5,774
Quoted Prices in Active Markets (Level 1) [Member]
Cash equivalents		139,010	[1]	5,119	[1]
Short-term investments		40	[2],[3]	205	[2],[3]
Total		139,050		5,324
Significant Other Observable Inputs (Level 2 ) [Member]
Cash equivalents					[1]
Short-term investments					[2],[3]
Total
Significant Unobservable Inputs (Level 3) [Member]
Cash equivalents					[1]
Short-term investments		450	[2],[3]	450	[2],[3]
Long-term investments		2,254	[4]
Total		2,704		450
Proceeds from redemption of investment at par	1,100	1,100	[3]
Significant Unobservable Inputs (Level 3) [Member] | Tax Advantaged Preferred Security [Member]
Short-term investments				0
Long-term investments		2,300
Percentage of investment to total assets		0.50%		0.00%
Significant Unobservable Inputs (Level 3) [Member] | Auction Rate Securities [Member]
Short-term investments		$ 400		$ 400
Percentage of investment to total assets		0.10%		0.10%

[1] Cash equivalents consist of money market funds with original maturity dates of three months or less, for which we determine fair value through quoted market prices.

[2] As of June 30, 2011 and December 31, 2010, Level 1 short-term investments include investments in tax-advantaged preferred securities, for which we determined fair value based on the quoted market prices of underlying securities.

[3] Level 3 short-term investments include an auction rate security invested in a tax-exempt state government obligation that was valued at par with a value of $0.4 million, or 0.1% of our total assets, as of both June 30, 2011 and December 31, 2010. Our intent is not to hold the auction rate security invested in a tax-exempt state government obligation to maturity, but rather to use the interest reset feature to provide liquidity. However, should the marketplace auctions continue to fail we may hold the security to maturity, which is September 2011. In October 2010, $1.1 million of this security was redeemed by the issuer at par.

[4] Level 3 long-term investments as of December 31, 2010 included a tax-advantaged preferred stock of a financial institution with a fair value of $2.3 million, or 0.5% of total assets. As of December 31, 2010, it was uncertain whether we would be able to liquidate these securities within the next twelve months; as such we classified them as long-term on our consolidated balance sheet. Due to the lack of observable market quotes we utilized valuation models that relied exclusively on Level 3 inputs including those that are based on expected cash flow streams, including assessments of counterparty credit quality, default risk underlying the security, discount rates and overall capital market liquidity. In June 2011, we sold this security for approximately $2.5 million and recorded a gain of approximately $0.4 million in our consolidated statement of operations.