Stock-Based Compensation (Detail) (USD $)	6 Months Ended		6 Months Ended		12 Months Ended	6 Months Ended			6 Months Ended					6 Months Ended		0 Months Ended			6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Stock appreciation rights (SARs)		Dec. 31, 2013 Stock appreciation rights (SARs)	Jun. 30, 2014 Restricted stock units (RSUs)		Dec. 31, 2013 Restricted stock units (RSUs)	Jun. 30, 2014 Restricted stock units (RSUs) Executive officer	Jun. 30, 2014 Restricted stock units (RSUs) Non executive	Jun. 30, 2014 Performance-based RSUs	Jun. 30, 2014 Common stock equivalents (CSEs)	Dec. 31, 2013 Common stock equivalents (CSEs)	Jun. 30, 2014 Target amount Restricted stock units (RSUs) Executive officer Minimum	Jun. 30, 2014 Target amount Restricted stock units (RSUs) Executive officer Maximum	May 29, 2014 2014 Long-Term Incentive Plan	May 29, 2014 2014 Long-Term Incentive Plan	Jun. 30, 2014 Unvested Stock appreciation rights (SARs)	Jun. 30, 2014 Employee stock purchase plan	Jun. 30, 2013 Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of transferred shares authorized																5,800,000.0
Number of additional shares authorized																2,200,000.0
Number of shares authorized																	8,000,000.0
Number of shares available for grant	7,970,000
Common stock par value (in Dollars per share)	$ 0.0005	$ 0.0005
Total share-based compensation cost not yet recognized	$ 58,400,000
Total share-based compensation cost not yet recognized, remaining weighted average service period	2 years 6 months		6 years 7 months 12 days
Award vesting period			4 years			4 years					4 years
Award expiry period from date of grant			7 years
Total compensation cost not yet recognized, period for recognition			4 years
Outstanding shares unvested			1,800,000	[1],[2]	1,600,000	1,400,000	[3],[4]	1,800,000				103,381	102,479					800,000
Aggregate Intrinsic value of outstanding shares			54,400,000
Aggregate intrinsic value of shares vested and exercisable			39,100,000
Stock grants during period			400,000			500,000	[5]		200,000	300,000		4,452
Percentage of shares authorized for grant														0.00%	200.00%
Weighted average remaining contractual terms			4 years 3 months 4 days	[1],[2]	4 years 4 months 2 days	1 year 6 months 10 days
Base fee percentage												50.00%
Employee stock purchase plan, stock purchases as percentage of employee compensation maximum																			10.00%
Maximum share value authorized for purchase under employee stock purchase plan																			23,750
Exercisable price percentage of closing price of another class of stock																			95.00%
Maximum number of shares that may be purchased by eligible participants																			1,100,000
Proceeds from stock plans																			$ 5,100,000	$ 3,400,000

[1] Total SARs outstanding had an intrinsic value of $54.4 million. SARs vested and exercisable had an intrinsic value of $39.1 million.

[2] As of June 30, 2014, 0.8 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.

[3] The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.5 years.

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

[5] The 0.5 million RSUs granted consisted of 0.2 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.2 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 2014. The final number of performance-based RSUs that will ultimately vest for 2014 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2014 as measured on December 31, 2014. 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.