Stock Options And Employee Stock Purchase Plan (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2012 Y	Jun. 30, 2011	Dec. 31, 2011
Weighted-average grant date fair value of options granted	$ 7.88	$ 13.12
Number of options outstanding	1,903,285		2,087,695
Number of options granted	57,000
Cash received upon the issuance of common stock	$ 61,000	$ 77,000
Percentage of stock options vested	20.00%
Expiration period of options granted (in years)	10
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	3,200,000	6,200,000
Stock Options [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	6,800,000		9,000,000
Restricted Stock And Restricted Stock Unit (RSU) [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	12,700,000		11,300,000
Employee Stock Purchase Plan [Member]
Market value of common stock on the date of grant for incentive stock options	95.00%
Maximum earnings withheld by the employees	15.00%
Number of shares purchased under the plan	2,432	2,840
Cash received upon the issuance of common stock	$ 61,000	$ 77,000
Number of shares available for issuance	1,648,966
Restricted Stock [Member]
Number of stocks outstanding	645,675		742,683
Restricted Stock Units (RSUs) [Member]
Number of stocks outstanding	95,416		32,750
1997 Stock Option Plan [Member]
Additional shares authorized for issuance	840,000
Maximum issuance of common stock	12,000,000
1997 Stock Option Plan [Member] | Stock Options [Member]
Number of options outstanding	816,977
1997 Stock Option Plan [Member] | Restricted Stock [Member]
Number of stocks outstanding	14,700
2007 Stock Plan [Member]
Number of options outstanding	1,086,308
Number of stocks outstanding	95,416
Maximum issuance of common stock	4,500,000
Minimum [Member]
Market value of common stock on the date of grant for incentive stock options	85.00%