Employee Savings Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan Disclosure [Line Items]
Minimum age to be eligible to defined contribution plan	21 years
Maximum contribution by company expressed as percentage of employee pre-tax salary	10000.00%
Company match percent	50.00%
Percent of employee contribution	6.00%
Company contributions vest at end of two years	25.00%
Company contributions vest at end of three years	50.00%
Company contributions vest at end of four years	75.00%
Company contributions vest at end of five years	100.00%
Company contributions to employee savings plan	$ 2,729,000	$ 2,540,000	$ 2,030,000