Investments	12 Months Ended
Dec. 31, 2011
Investments [Abstract]
Investments	(3) Investments At December 31, 2011, the Company held $19.9 million of municipal and corporate variable rate demand notes, all of which were classified as available-for-sale. All municipal and corporate variable rate demand notes at December 31, 2011, contain put options of seven days. The Company routinely buys and sells these securities and believes that it has the ability to quickly liquidate them. The Company's investments in these securities are recorded at fair value and the interest rates reset every seven days. The Company believes we have the ability to tender our variable rate demand notes to the tender agent (agent to the issuer) or issuer at par value plus accrued interest in the event we decide to liquidate our investment in a particular variable rate demand note. At December 31, 2011, all of the Company's variable rate demand notes were supported by irrevocable direct pay letters of credit from a financial institution that the Company believes to be in good financial condition. As a result of these factors, the Company had no cumulative gross unrealized holding gains (losses) or gross realized gains (losses) from these investments. All income generated from these investments is recorded as interest income. The Company has not recorded any losses relating to municipal or corporate variable rate demand notes. On October 17, 2011, the Company invested $20.0 million in a 183-day time deposit issued by Credit Agricole Corporate and Investment Bank maturing on April 17, 2012. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2011. On October 15, 2010, the Company invested $20.0 million in a 182-day time deposit issued by Credit Agricole Corporate and Investment Bank that matured on April 15, 2011. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2010. On August 10, 2010, the Company invested $20.0 million in a 157-day time deposit issued by Credit Agricole Corporate and Investment Bank that matured on January 14, 2011. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2010. The Company held $58.7 million par value of auction rate securities as of December 31, 2009, with a fair value of $54.2 million. The auction rate securities were secured by pools of student loans guaranteed by state-designated guaranty agencies or monoline insurers or reinsured by the United States government and were senior obligations of the issuers. The Company received full redemptions of these securities, at par, during 2010.

(3) Investments

At December 31, 2011, the Company held $19.9 million of municipal and corporate variable rate demand notes, all of which were classified as available-for-sale. All municipal and corporate variable rate demand notes at December 31, 2011, contain put options of seven days. The Company routinely buys and sells these securities and believes that it has the ability to quickly liquidate them. The Company's investments in these securities are recorded at fair value and the interest rates reset every seven days. The Company believes we have the ability to tender our variable rate demand notes to the tender agent (agent to the issuer) or issuer at par value plus accrued interest in the event we decide to liquidate our investment in a particular variable rate demand note. At December 31, 2011, all of the Company's variable rate demand notes were supported by irrevocable direct pay letters of credit from a financial institution that the Company believes to be in good financial condition. As a result of these factors, the Company had no cumulative gross unrealized holding gains (losses) or gross realized gains (losses) from these investments. All income generated from these investments is recorded as interest income. The Company has not recorded any losses relating to municipal or corporate variable rate demand notes.

On October 17, 2011, the Company invested $20.0 million in a 183-day time deposit issued by Credit Agricole Corporate and Investment Bank maturing on April 17, 2012. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2011.

On October 15, 2010, the Company invested $20.0 million in a 182-day time deposit issued by Credit Agricole Corporate and Investment Bank that matured on April 15, 2011. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2010.

On August 10, 2010, the Company invested $20.0 million in a 157-day time deposit issued by Credit Agricole Corporate and Investment Bank that matured on January 14, 2011. The investment is classified as held-to-maturity and carried at amortized cost of $20.0 million in the accompanying balance sheet at December 31, 2010.

The Company held $58.7 million par value of auction rate securities as of December 31, 2009, with a fair value of $54.2 million. The auction rate securities were secured by pools of student loans guaranteed by state-designated guaranty agencies or monoline insurers or reinsured by the United States government and were senior obligations of the issuers. The Company received full redemptions of these securities, at par, during 2010.