Stock Option Plans (Schedule Of Stock Option Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Stock Option Plans [Abstract]
Shares, beginning balance	12,739,831
Shares, Granted	2,828,125
Shares, Exercised	(1,669,489)
Shares, Forfeited/expired	(143,899)
Shares, ending balance	13,754,568
Shares, Expected to vest	13,204,038
Shares, Options exercisable	7,823,456
Weighted-average exercise price per share, beginning balance	$ 9.94
Weighted-average exercise price per share, Granted	$ 16.45
Weighted-average exercise price per share, Exercised	$ 7.38
Weighted-average exercise price per share, Forfeited/expired	$ 12.73
Weighted-average exercise price per share, ending balance	$ 11.55
Weighted-average exercise price per share, Expected to vest	$ 11.43
Weighted-average exercise price per share, Options exercisable	$ 9.60
Weighted-average remaining contractual term (in years), Options outstanding	$ 7.19
Weighted-average remaining contractual term (in years), Expected to vest	$ 7.08
Weighted-average remaining contractual term (in years), Options exercisable	$ 5.96
Aggregate intrinsic value, Options outstanding	$ 72,667
Aggregate intrinsic value, Expected to vest	71,326
Aggregate intrinsic value, Options exercisable	$ 55,664