Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2015
Variable Interest Entity [Line Items]
Contribution liability	$ 2,509,234	$ 2,337,665
Cloverleaf
Variable Interest Entity [Line Items]
Original benefit of contribution by tax credit investor's			$ 5,600
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Contribution liability	$ 4,800	$ 4,900