Share-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (in years)	10 years
Unvested options to purchase	3.5	2.8
Weighted average grant date value	$ 44.55	$ 27.20
Total unrecognized compensation cost	$ 48.3
Weighted average amortization period (in years)	4 years
Share Based Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	1.1
Shares reserved for future issuance	16.0
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance	1.0
Percentage of annual compensation participants may contribute	15.00%
Purchase price as a percentage of closing price on the last day of the quarter for ESPP transactions	85.00%
Employee Stock Purchase Plan [Member] | Previously Approved by Stockholders [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance	2.0
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	6 years