Stock-Based Compensation Expense

9 Months Ended

Sep. 30, 2011

Stock-Based Compensation Expense [Abstract]

Stock-Based Compensation Expense

7. Stock-Based Compensation Expense

Stock-based compensation is measured at the grant date based on the fair value of the award, and recognized as an expense over the requisite service period, net of an estimated forfeiture rate. We issue four types of stock-based compensation awards: stock options, restricted common stock, restricted stock units, and performance stock units. For further information, see Notes 2 and 11 included in our Annual Report on Form 10-K for the year ended December 31, 2010 filed with the SEC on February 18, 2011.

The following summarizes stock-based compensation expense recognized for the three and nine months ended September 30, 2011 and 2010 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2011		2010		2011		2010
Stock options	$	1,209	$	1,478	$	3,709	$	4,503
Restricted common stock		33		300		321		1,414
Restricted stock units		1,299		938		3,953		2,411
Performance stock units		204		134		730		351
Total stock-based compensation expense	$	2,745	$	2,850	$	8,713	$	8,679