Stock-Based Compensation (Detail) - Summary Of Changes In RSUs Outstanding (Restricted stock units (RSUs), USD $)	6 Months Ended
	Jun. 30, 2013
Restricted stock units (RSUs)
Restricted Stock Units (RSUs) [Roll Forward]
Outstanding at December 31, 2012 (in shares)	2,500,000
Granted (in shares)	600,000	[1]
Vested and released (in shares)	(1,300,000)
Forfeited (in shares)	0
Outstanding at June 30, 2013 (in shares)	1,800
Per Share Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at December 31, 2012 (in dollars per share)	$ 27.95
Granted (in Dollars per share)	$ 49.71	[1]
Vested and released (in Dollars per share)	$ 22.44
Forfeited (in Dollars per share)	$ 0.0
Outstanding at June 30, 2013 (in Dollars per share)	$ 38,650

[1] The 0.6 million RSUs granted in 2013 consisted of 0.3 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.3 million performance-based RSUs 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 2013. The final number of performance-based RSUs that will be granted to executives in 2013 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for the year as measured on December 31, 2013. 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.