Stock Option Plans and Share-Based Compensation-Narrative (Details) (USD $)	12 Months Ended							12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2010 2009 Equity Incentive Plan [Member]	Dec. 31, 2012 2009 Equity Incentive Plan [Member]	May 19, 2009 2009 Equity Incentive Plan [Member]	Dec. 31, 2012 2009 Equity Incentive Plan [Member] Stock Options [Member] VestingInstallment	Dec. 31, 2012 Employee Stock Purchase Plan [Member]	Dec. 31, 2009 Employee Stock Purchase Plan [Member]	Dec. 31, 2012 Employee Stock Purchase Plan [Member] Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized							2,100,000
Number of shares not available for grant for each share granted					1.8	1.4
Number of additional shares authorized					2,600,000					2,622,426
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant						1,636,329
Award vesting period								4 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Monthly Vesting Installments After Initial Cliff								36
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period								10 years
Maximum annual contribution per employee, percent									15.00%
Maximum annual contribution per employee									$ 25,000
Purchase price of stock, percent											85.00%
Offering period											24 months
Purchasing period											6 months
Number of shares available for grant									1,548,711
Stock Issued During Period, Shares, Employee Stock Purchase Plans									377,849
Stock Issued Since Plan Inception, Shares Employee Stock Purchase Plans									3,782,844
Total compensation cost not yet recognized				6,600,000.00					500,000
Period for recognition				2 years 9 months 18 days					1 year 9 months 15 days
Maximum employee subscription rate contribution per employee, percent	75.00%
Employer matching contribution, percent	3.00%
Maximum annual contribution per employee	1,000
Cost recognized	$ 800,000	$ 600,000	$ 500,000
Share vesting rate	25.00%