Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease asset	$ 489
Liability - operating lease	492
Prepaid expenses and other assets	1,574	$ 1,354	$ 1,382
Other noncurrent assets	533	645	32
Accrued expenses and other current liabilities	1,781	1,786	1,543
Other noncurrent liabilities	$ 226	381	$ 39
ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease asset		613
Liability - operating lease		623
Prepaid expenses and other assets		(28)
Other noncurrent assets		613
Accrued expenses and other current liabilities		243
Other noncurrent liabilities		$ 342