Summary Of Changes In RSUs Outstanding (Detail) (Restricted Stock Units, USD $)	6 Months Ended
	Jun. 30, 2012
Restricted Stock Units
Restricted Stock Units
Beginning Balance	3,100,000
Granted	700,000	[1]
Vested and released	(1,300,000)
Forfeited
Ending Balance	2,500,000	[2],[3]
Per Share Weighted Average Grant Date Fair Value
Beginning Balance	$ 21.53
Granted	$ 37.96	[1]
Vested and released	$ 19.47
Forfeited
Ending Balance	$ 27.92	[2],[3]

[1] The 0.7 million RSUs granted in 2012 consisted of 0.3 million performance-based RSUs awarded to executives and 0.4 million service-based RSUs awarded to non-executive employees and certain board members. The 0.3 million performance-based RSUs awarded to executives represents the target amount of the award for the year, which is tied to an increase in the Company's subscription-based Research contract value ("CV") for 2012. The final number of performance-based RSUs that will be granted to executives in 2012 could range from 0% to 200% of the target amount, depending on the actual increase in CV for the year as measured on December 31, 2012. If the specified minimum level of achievement is not met, the performance-based RSUs will be forfeited in their entirety, and any compensation expense previously recorded will be reversed.

[2] The Company expects that substantially all of the outstanding awards will vest in future periods.

[3] The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.4 years.