Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning balance	$ 1,039	$ 651	$ 419
Additions for tax positions in current years	536	388	232
Additions for tax positions in prior years	0	0	0
Reductions due to lapse in statutes of limitations	0	0	0
Settlements	0	0	0
Ending balance	$ 1,575	$ 1,039	$ 651