Employee Benefit Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Maximum employee contribution to 401k	50.00%
Employer match for first 6% contributed by plan participant	50.00%
Maximum contribution by participant that employer will match at 50%	6.00%
Maximum annual contribution by employer	$ 3,000
Employer contribution to the plan	$ 2,900,000	$ 2,700,000	$ 2,600,000