Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balances at beginning of the year	$ 1,614	$ 1,614
Additions based on tax position related to current year
Balance at the end of year	1,614	1,614
Accrued interest and penalties on unrecognized tax benefits	$ 0	$ 0	$ 0