Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Income Tax Examination [Line Items]
Income tax expense	$ 8	$ 24
Effective income tax rate reconciliation, percent	0.09%	0.50%
Operating loss carryforwards			$ 45,000
Not Subject to Limitations | Subsequent To Change Date In 2010
Income Tax Examination [Line Items]
Operating loss carryforwards			26,500
Subject to Limitations | Minimum
Income Tax Examination [Line Items]
Operating loss carryforwards			1,000
Subject to Limitations | Maximum
Income Tax Examination [Line Items]
Operating loss carryforwards			$ 2,300