Stock based Compensation

6 Months Ended

Jun. 30, 2011

Stock based Compensation [Abstract]

Stock based Compensation

(8) Stock-based Compensation

In 2011, we granted the following shares of common stock, restricted stock awards, restricted stock units and options for the purchase of shares of our common stock. For all grants except stock options, we measure fair value based on our closing stock price on the grant date. For stock options, we use the Black-Scholes single option pricing model to determine the fair value of an option on its grant date. The fair value of the common stock was expensed on the grant date. The fair value of the restricted stock awards, restricted stock units and stock options will be expensed over the vesting period.

			Weighted-average
	Number		grant date		Aggregate		Vesting
	of shares		fair value		fair value		period
Common stock		28	$	32.54	$	920		—
Restricted stock awards		289		31.22		9,023	3-5 years
Restricted stock units		65		30.25		1,952	4 years
Stock options		179		7.36		1,317	1-5 years