Short-Term Investments	6 Months Ended
Jun. 30, 2011
Short-Term Investments [Abstract]
Short-Term Investments	(5) Short-Term Investments The Company’s short-term investments consist of U.S. treasury bills and notes that are issued by the U.S. government, all of which are accounted for as trading securities. Trading securities are recorded at fair value with the unrealized holding gains and losses included in net income. Included in interest expense, net is $0.2 million of income for the six months ended June 30, 2011 related to this trading portfolio. The Company intends to use these funds along with $145.9 million of cash and cash equivalents, that have been segregated and dedicated, for a total of $310.1 million to partially fund the redemption of the $400.0 million aggregate principal amount of all of the outstanding 1.50% senior exchangeable notes due 2026. The 1.50% senior exchangeable notes become subject to redemption on December 15, 2011 at a redemption price of 100% of the principal amount of the notes outstanding (see note 8).

(5) Short-Term Investments

The Company’s short-term investments consist of U.S. treasury bills and notes that are issued by the U.S. government, all of which are accounted for as trading securities. Trading securities are recorded at fair value with the unrealized holding gains and losses included in net income. Included in interest expense, net is $0.2 million of income for the six months ended June 30, 2011 related to this trading portfolio. The Company intends to use these funds along with $145.9 million of cash and cash equivalents, that have been segregated and dedicated, for a total of $310.1 million to partially fund the redemption of the $400.0 million aggregate principal amount of all of the outstanding 1.50% senior exchangeable notes due 2026. The 1.50% senior exchangeable notes become subject to redemption on December 15, 2011 at a redemption price of 100% of the principal amount of the notes outstanding (see note 8).