Commitments and Contingencies (Details)	Sep. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Aggregate face amount of letter of credit agreements	$ 15,000,000
Performance Guarantee [Member]
Loss Contingencies [Line Items]
Liability for guarantees	0
U.S. Treasury securities [Member]
Loss Contingencies [Line Items]
U.S. Treasury securities posted as collateral	242,000,000
Margin Requirements [Member]
Loss Contingencies [Line Items]
Funds drawn under LOC's	$ 0