Stockholders' Equity - Stock Options Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding , Shares	9,287,901	10,720,200
Weighted Average Contractual Term, Outstanding	6 years 6 months 14 days
Range 1 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 2.10
Exercise Price Range, Upper	$ 3.57
Options Outstanding , Shares	940,493
Weighted Average Contractual Term, Outstanding	6 years 1 month 20 days
Range 2 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 4.50
Exercise Price Range, Upper	$ 6.60
Options Outstanding , Shares	574,174
Weighted Average Contractual Term, Outstanding	5 years 4 months 9 days
Range 3 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 6.62
Exercise Price Range, Upper	$ 6.62
Options Outstanding , Shares	991,898
Weighted Average Contractual Term, Outstanding	7 years 25 days
Range 4 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 6.66
Exercise Price Range, Upper	$ 7.98
Options Outstanding , Shares	890,168
Weighted Average Contractual Term, Outstanding	5 years 5 months 1 day
Range 5 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 8.19
Exercise Price Range, Upper	$ 8.19
Options Outstanding , Shares	961,252
Weighted Average Contractual Term, Outstanding	5 years 1 month 24 days
Range 6 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 8.22
Exercise Price Range, Upper	$ 10.82
Options Outstanding , Shares	590,192
Weighted Average Contractual Term, Outstanding	6 years 5 months 8 days
Range 7 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 10.86
Exercise Price Range, Upper	$ 10.86
Options Outstanding , Shares	980,448
Weighted Average Contractual Term, Outstanding	8 years 1 month 17 days
Range 8 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 10.91
Exercise Price Range, Upper	$ 10.94
Options Outstanding , Shares	78,800
Weighted Average Contractual Term, Outstanding	6 years 9 months 18 days
Range 9 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 11.02
Exercise Price Range, Upper	$ 11.02
Options Outstanding , Shares	1,109,583
Weighted Average Contractual Term, Outstanding	9 years 2 months 1 day
Range 10 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 11.56
Exercise Price Range, Upper	$ 29.76
Options Outstanding , Shares	2,170,893
Weighted Average Contractual Term, Outstanding	5 years 9 months 18 days