Preferred Stock, Common Stock and Equity Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Preferred Stock, Common Stock and Equity Plans
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, shares authorized	300,000,000	300,000,000
Number of votes per share holders of common stock are entitled to	one
Share-based Compensation Arrangement by Share-based Payment Award
Awards outstanding (in shares)	23,067,233	21,293,000
Additional awards authorized for grant (in shares)	8,631,417
Grant price of outstanding restricted stock and restricted stock units (in dollars per share)	$ 0.01
Outstanding and vested options
Stock options outstanding at beginning of period (in shares)	21,293,000
Stock options outstanding at end of period (in shares)	23,067,233	21,293,000
Weighted average Exercise Price
Weighted-average Exercise Price outstanding at beginning of period (in dollars per share)	$ 30.50
Weighted average exercise price, granted (in dollars per share)	$ 43.55
Weighted average exercise price, exercised (in dollars per share)	$ 26.60
Weighted average exercise price, forfeited (in dollars per share)	$ 36.78
Weighted average exercise price, expired (in dollars per share)	$ 37.81
Weighted average exercise price exercisable at the end of the period (in dollars per share)	$ 30.59
Total exercisable or expected to vest, weighted average exercise price (in dollars per share)	$ 33.94
Weighted-average Exercise Price outstanding at end of period (in dollars per share)	$ 34.23	$ 30.50
Weighted-average Remaining Contractual Life
Weighted-average Remaining Contractual Life, outstanding (in years)	6.84
Weighted-average Remaining Contractual Life, exercisable (in years)	5.55
Weighted-average Remaining Contractual Life, total exercisable or expected to vest (in years)	6.74
Aggregate Intrinsic Value
Aggregate intrinsic value, outstanding	$ 56,376,000
Aggregate intrinsic value, exercisable	53,552,000
Aggregate intrinsic value, total exercisable or expected to vest	56,108,000
Aggregate intrinsic value of shares, market price (in dollars per share)	$ 32.92
Total Intrinsic Value and Cash Received
Total intrinsic value of stock options exercised	90,500,000	10,500,000	36,400,000
Total cash received from employees as a result of employee stock option exercises	$ 109,600,000	$ 22,200,000	$ 38,200,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Awards outstanding (in shares)	20,923,000
Maximum period within which stock options expires (in years)	10
Outstanding and vested options
Stock options outstanding at beginning of period (in shares)	21,293,000
Stock options granted (in shares)	5,754,000
Stock options exercised (in shares)	(4,119,000)
Stock options forfeited (in shares)	(1,554,000)
Stock options expired (in shares)	(451,000)
Stock options outstanding at end of period (in shares)	20,923,000
Stock options exercisable at end of period (in shares)	12,225,000
Total exercisable or expected to vest, stock options (in shares)	19,922,000
2006 Stock and Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Awards outstanding (in shares)	19,889,776
Additional awards authorized for grant (in shares)	8,631,417
Approved increase in number of shares authorized for issuance (in shares)		12,000,000	7,700,000
Outstanding and vested options
Stock options outstanding at end of period (in shares)	19,889,776
1996 Stock and Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Awards outstanding (in shares)	3,177,457
Outstanding and vested options
Stock options outstanding at end of period (in shares)	3,177,457
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Common stock authorized for employee stock purchase plan	482,000
Number of shares (in shares)	557,000
Average price paid per share	$ 27.47
Offering period for employee stock purchase plan	twelve-month offering
Bifurcation of offering period	two six-month
Purchase of shares at discounted fair market value of common stock (as a percent)	85.00%