Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Provision for income tax	$ 5	$ 8	$ 10	$ 14
Effective income tax rate	0.10%	0.40%	0.10%	0.30%