Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Deferred tax asset, valuation allowance	$ 104,298,000	$ 75,436,000	$ 58,748,000	$ 59,806,000
Unrecognized tax benefits	9,824,000	7,240,000	$ 5,496,000	$ 0
Unrecognized tax benefits recorded as deferred tax asset reduction	9,800,000
Unrecognized tax benefits, income tax penalties and interest accrued	0	0
EZ Hiring Credit
Income Taxes [Line Items]
Tax credit carryforward	2,200,000	2,200,000
Federal
Income Taxes [Line Items]
Operating loss carryforward	251,000,000.0	152,100,000
Federal | Research and Development Credit
Income Taxes [Line Items]
Tax credit carryforward	10,600,000
State
Income Taxes [Line Items]
Operating loss carryforward	70,300,000	49,600,000
State | Research and Development Credit
Income Taxes [Line Items]
Tax credit carryforward	9,000,000.0
Foreign
Income Taxes [Line Items]
Operating loss carryforward	13,500,000	12,200,000
Tax credit carryforward	$ 200,000	$ 100,000