Stock-Based Compensation (Detail) - Summary Of Changes In RSUs Outstanding (Restricted stock units (RSUs), USD $)	3 Months Ended
	Mar. 31, 2015
Restricted stock units (RSUs)
Restricted Stock Units (RSUs) [Roll Forward]
Outstanding at December 31, 2014 (in shares)	1,400,000
Granted (in shares)	600,000	[1]
Vested and released (in shares)	(600,000)
Outstanding at March 31, 2015 (in shares)	1,400,000	[2],[3]
Per Share Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at December 31, 2014 (in Dollars per share)	$ 50.76
Granted (in Dollars per share)	$ 78.02	[1]
Vested and released (in Dollars per share)	$ 47.03
Outstanding at March 31, 2015 (in Dollars per share)	$ 62.18	[2],[3]

[1] The 0.6 million RSUs granted consisted of 0.4 million performance-based RSUs awarded to executives and 0.2 million service-based RSUs awarded to non-executive employees and non-management board members. The 0.4 million performance-based RSUs represents the target amount of the grant for the year, which is tied to an increase in the Company’s subscription-based research contract value (“CV”) for 2015. The final number of performance-based RSUs that will ultimately be awarded for 2015 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2015 as measured on December 31, 2015. 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 weighted-average remaining contractual term of the outstanding RSUs is approximately 1.8 years.

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