Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at January 1	$ 2,642	$ 1,146	$ 531
Additions for tax positions taken in a prior year	107	0	0
Additions for tax positions taken in the current year	2,595	1,506	640
Reductions for tax positions taken in the prior year	(45)	(10)	(25)
Unrecognized tax benefits at December 31	$ 5,299	$ 2,642	$ 1,146