Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended				6 Months Ended	12 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Employee Stock Option [Member] Y	Feb. 29, 2012 Employee Stock Option [Member]	Jun. 30, 2012 Non-Vested Stock Unit Awards [Member] Y	Dec. 31, 2011 Non-Vested Stock Unit Awards [Member]	Jun. 30, 2012 Market and Service Condition Stock Units [Member]
Stock option vesting period			3 years
Stock options lifespan			5 years
Expected dividend yield	0.00%	0.00%	0.00%	0.00%					0.00%
Shares authorized for issuance under 2005 Equity Incentive Plan	48,600,000		48,600,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized						5,500,000
Ownership percentage of company where incentive stock options must be granted with an exercise price greater than fair market value			10.00%
Exercise price of incentive stock options granted to individuals owning 10% or more of the Company's common stock, as a percentage of fair market value of common stock on the date of grant			110.00%
Shares reserved for issuance under the 2005 Equity Incentive Plan	32,025,718		32,025,718
Shares available for grant under the 2005 Equity Incentive Plan	19,302,687		19,302,687
Employee Stock Purchase Plan, minimum payroll deduction as a percentage of base pay			1.00%
Employee Stock Purchase Plan, maximum payroll deduction as a percentage of base pay			10.00%
Employee Stock Purchase Plan, maximum number of shares per period that employees can purchase	12,000		12,000
Employee Stock Purchase Plan, purchase price as a percentage of fair market value			85.00%
Employee Stock Purchase Plan, employee disqualification, ownership percent of outstanding stock			5.00%
Employee Stock Purchase Plan, authorized shares under plan			10,000,000
Employee Stock Purchase Plan, total shares issued under plan			2,395,553
The Company recorded stock based compensation costs related to the 2005 ESPP	$ 0.9		$ 1.9
Stock-based compensation award vesting period, percentage of award vesting each year					33.30%		33.33%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period									418,809
Maximum Percentage of Market and Service Condition Stock Units That will Ultimately Vest									200.00%
Percentage That Company's Return Exceeds Indexed Return			40.00%
Percentage That Company's Return Underperforms Index	20.00%
Share Based Compensation Arrangement By Share Based Payment Award, Percent Vested on Third Anniversary of Grant Date								100.00%
Stock-based compensation award vesting period, percentage of award vesting each month					2.78%
The weighted average fair value per share of stock options granted	$ 27.57
The total intrinsic value of options exercised	38.0		77.2
Total unrecognized compensation cost related to stock-based compensation					$ 92.6		$ 224.1
Total unrecognized compensation cost recognition period (in years)					1.93		2.44
Share based awards granted and outstanding							3,572,163
Performance goal, percentage of attainment required to earn performance-based award							90.00%
Minimum percentage of performance-based awards that will ultimately vest							90.00%
Maximum percentage of performance-based awards that will ultimately vest							125.00%
The estimated fair value of each award									$ 89.95
Percent of award issued if return is negative but index is met									75.00%