Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($)	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]
Liabilities for Unrecognized Tax Benefits at Beginning of Year	$ 0	$ 4,400,000	$ 8,100,000
Additions for Tax Positions of Current Year	0	0	700,000
Reductions for Tax Positions of Prior Years	0	(4,400,000)	(4,400,000)
Liabilities for Unrecognized Tax Benefits at End of Year	$ 0	$ 0	$ 4,400,000