Commitments and Contingencies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Other Commitments [Line Items]
Purchase orders outstanding	$ 3.0
Purchase orders outstanding, term	3 months
Performance Guarantee
Other Commitments [Line Items]
Bonds outstanding	$ 1,360.0
Estimated remaining costs for bonded projects	660.2
Contingencies Excluding Wildfire and Health Insurance
Other Commitments [Line Items]
Insurance coverage deductible	1.0
Wildfire
Other Commitments [Line Items]
Insurance coverage deductible	2.0
Health Insurance
Other Commitments [Line Items]
Insurance coverage deductible	$ 0.2