Fair Value Measurements - Stock Option Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reclass of stock options from liability to equity classification	$ 37,700
Stock Option Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	43,026	$ 64,250
Settlement of stock options	(896)	(33,901)
Exercise of stock options	(235)	(1,442)
Change in fair value	(9,656)	8,356
Amortization of grant date fair value	5,422	5,763
Reclassifications from liability to equity	(37,661)	0
Ending balance	$ 0	$ 43,026