Subsequent Events	12 Months Ended
Dec. 31, 2012
Subsequent Events
Subsequent Events	11. Subsequent Events Convertible Subordinated Notes Due 2023 On January 24, 2013, the Company completed an underwritten public offering of $287.5 million aggregate principal amount of unsecured 2.125% convertible subordinated notes due 2023, which includes the full exercise of the underwriters' over-allotment option for $37.5 million aggregate principal amount. The financing raised proceeds, net of issuance costs, of approximately $244.4 million. The notes are convertible into shares of the Company's common stock at an initial conversion rate of 35.9903 shares per $1,000 principal amount of the notes, subject to adjustment in certain circumstances, which represents an initial conversion price of approximately $27.79 per share. In connection with the offering of the notes, the Company entered into privately-negotiated capped call option transactions. The capped call option transaction is an integrated instrument consisting of a call option purchased by the Company with a strike price equal to the conversion price of $27.79 per share for the underlying number of shares and a cap price of $38.00 per share. The cap component is economically equivalent to a call option sold by the Company for the underlying number of shares with a strike price of $38.00 per share. As an integrated instrument, the settlement of the capped call coincides with the due date of the convertible debt. At settlement, the Company will receive from its hedge counterparty a number of our common shares that will range from zero, if the stock price is below $27.79 per share, to a maximum of 2,779,659 shares, if the stock price is above $38.00 per share. However, if the market price of our common stock, as measured under the terms of the capped call transactions, exceeds $38.00 per share, there is no incremental anti-dilutive benefit from the capped call. The aggregate cost of the capped call options was $36.8 million. Sale of Stock On February 15, 2013, the Company and GSK entered into an agreement pursuant to which GSK agreed to purchase through an affiliate, in a private placement, 116,527 shares of the Company's common stock at $22.03 per share, for an aggregate purchase price of approximately $2.6 million, pursuant to its rights under the Company's governance agreement with GSK dated June 4, 2004, as amended.

11. Subsequent Events

Convertible Subordinated Notes Due 2023

On January 24, 2013, the Company completed an underwritten public offering of $287.5 million aggregate principal amount of unsecured 2.125% convertible subordinated notes due 2023, which includes the full exercise of the underwriters' over-allotment option for $37.5 million aggregate principal amount. The financing raised proceeds, net of issuance costs, of approximately $244.4 million. The notes are convertible into shares of the Company's common stock at an initial conversion rate of 35.9903 shares per $1,000 principal amount of the notes, subject to adjustment in certain circumstances, which represents an initial conversion price of approximately $27.79 per share.

In connection with the offering of the notes, the Company entered into privately-negotiated capped call option transactions. The capped call option transaction is an integrated instrument consisting of a call option purchased by the Company with a strike price equal to the conversion price of $27.79 per share for the underlying number of shares and a cap price of $38.00 per share. The cap component is economically equivalent to a call option sold by the Company for the underlying number of shares with a strike price of $38.00 per share. As an integrated instrument, the settlement of the capped call coincides with the due date of the convertible debt. At settlement, the Company will receive from its hedge counterparty a number of our common shares that will range from zero, if the stock price is below $27.79 per share, to a maximum of 2,779,659 shares, if the stock price is above $38.00 per share. However, if the market price of our common stock, as measured under the terms of the capped call transactions, exceeds $38.00 per share, there is no incremental anti-dilutive benefit from the capped call. The aggregate cost of the capped call options was $36.8 million.

Sale of Stock

On February 15, 2013, the Company and GSK entered into an agreement pursuant to which GSK agreed to purchase through an affiliate, in a private placement, 116,527 shares of the Company's common stock at $22.03 per share, for an aggregate purchase price of approximately $2.6 million, pursuant to its rights under the Company's governance agreement with GSK dated June 4, 2004, as amended.