Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Federal and state net operating loss carry forwards	$ 137,138	$ 61,009
Federal and state tax credits	32,707	23,195
Valuation allowance	155,841	40,966
Increase in valuation allowance	114,900
Unrecognized tax benefits that would impact effective tax rate	400
Unrecognized tax benefit with uncertainty about timing of deductibility	4,400
Accrued interest	$ 200	$ 800
Minimum
Income Taxes [Line Items]
Period of income tax returns examination after filing	3 years
Maximum
Income Taxes [Line Items]
Period of income tax returns examination after filing	5 years