Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at the beginning of the year	$ 52,832	$ 39,710
Additions to unrecognized tax benefits related to current year	0	0
Additions to unrecognized tax benefits related to prior years	2,446	13,122
Unrecognized tax benefit at the end of the year	$ 55,278	$ 52,832