Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percent of pre-tax income:
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
State taxes, net of federal benefit	18.50%	14.60%	2.80%
Permanent items	4.00%	4.00%	(1.40%)
Remeasurement of deferred tax assets	0.00%	49.90%	0.00%
Impact of state rate changes	(0.20%)	(27.90%)	(11.00%)
Research and development credit	(2.40%)	(0.00%)	1.90%
Alternative minimum tax credit	0.00%	(1.30%)	1.10%
Change in valuation allowance	(42.60%)	(78.60%)	(28.20%)
Effective income tax rate	(1.70%)	(4.30%)	0.20%