Employee Benefits And Stock-Based Compensation (401(k) Plan To 2007 Employee Stock Purchase Plan) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 word Rate	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contribution under the plan	$ 2.8	$ 2.9	$ 4.1
Common stock were reserved for issuance	15.4
Minimum exercise price as percentage of the fair market value on grant date	100.00%
Vesting period of options assumed (in years)	4
Stock-based compensation expense related to vested RSUs	$ 9.2
Purchase price of common stock as percentage of lower of fair market value of common stock share on first day of offering period or last day of purchase period	85.00%
401 (k) Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Employer Contribution As A Percentage Of Employee Contribution	50.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of Options/RSUs	25.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of Options/RSUs	25.00%
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock were reserved for issuance	2.6
Two Thousand Seven Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock were reserved for issuance	6.0
Two Thousand Six Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock were reserved for issuance	27.0
Maximum terms of award from date of grant (years)	7
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of options assumed (in years)	7
Minimum [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of compensation withheld to cover purchase price of common stock	2.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of options assumed (in years)	10
Maximum [Member] | 401 (k) Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee's contribution under the plan	20.00%
Employer contribution as a percentage of employee's annual salary	6.00%
Maximum [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of compensation withheld to cover purchase price of common stock	25.00%