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]
Balance at beginning of the period	$ 33,920	$ 19,549	$ 3,814
Increases related to current period tax positions	26,653	14,407	9,704
Increases related to prior period tax positions	26,732	598	6,031
Decreases related to prior period tax positions	0	(156)	0
Settlement with tax authorities	0	(478)	0
Statute of limitations expiration	(657)	0	0
Balance at end of period	$ 86,648	$ 33,920	$ 19,549