Net loss per share (Tables)

3 Months Ended

Mar. 31, 2013

Net loss per share

Schedule of antidilutive securities excluded from the computation of earnings per share

	2013	2012
Outstanding stock options	24,208,663	24,729,232
Common shares issuable upon conversion of 4.75% Senior Notes	45,583,814	45,584,040
Common shares issuable upon conversion of Pfizer Note due 2013(1)	—	1,461,496
Common shares issuable upon conversion of Pfizer Note due 2014	1,025,641	1,025,641
Total potential common shares excluded from diluted net loss per share computation	70,818,118	72,800,409

(1) In December 2012, the holder of the Pfizer Note due 2013 elected to convert all $10.0 million principal amount into 1,461,496 shares of common stock.