Income Taxes - Reconciliation of Liability for Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at January 1	$ 2,404	$ 272	$ 19
Addition for tax positions taken in the prior years	133	32
Reduction for tax positions taken in the prior years	(1,596)	(215)
Addition for tax positions taken in current year	1,784	2,315	253
Gross unrecognized tax benefits at December 31	$ 2,725	$ 2,404	$ 272