Commitments and Contingencies - Environmental Matters (Details)		12 Months Ended
	May 09, 2017	Dec. 31, 2002 USD ($) a water_company respondent	Dec. 31, 2021 USD ($) environmental_matter	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 31, 2001 USD ($)
Site Contingency [Line Items]
Number of environmental remediation matters (over) | environmental_matter			40
Accrued environmental costs			$ 296,400,000	$ 300,600,000	$ 309,200,000	$ 327,900,000
Guarantee obligations			120,000,000
Various Environmental Matters
Site Contingency [Line Items]
Accrued environmental costs			296,400,000
Various Environmental Matters | Sacramento, California
Site Contingency [Line Items]
Accrued environmental costs			214,700,000
Various Environmental Matters | Sacramento, California | Environmental Protection Agency
Site Contingency [Line Items]
Non-contaminated land | a		2,600
Various Environmental Matters | Sacramento, California | Previously Reported
Site Contingency [Line Items]
Guarantee obligations		$ 20,000,000
Various Environmental Matters | Baldwin Park Operable Unit
Site Contingency [Line Items]
Accrued environmental costs			$ 64,700,000
Guarantee obligations							$ 25,000,000
Various Environmental Matters | Baldwin Park Operable Unit | Aerojet Rocketdyne Inc
Site Contingency [Line Items]
Percentage of responsibility in all project costs			74.00%
Various Environmental Matters | Baldwin Park Operable Unit | Environmental Protection Agency
Site Contingency [Line Items]
Number of respondents | respondent		7
Number of water companies | water_company		5
Term of arrangement (years)	10 years
Various Environmental Matters | Contracting business
Site Contingency [Line Items]
Environmental obligation funding percent			98.00%
Various Environmental Matters | Minimum
Site Contingency [Line Items]
Estimated environmental costs			$ 296,400,000
Various Environmental Matters | Minimum | Sacramento, California
Site Contingency [Line Items]
Estimated environmental costs			214,700,000
Guarantee obligations		$ 10,000,000
Various Environmental Matters | Minimum | Baldwin Park Operable Unit
Site Contingency [Line Items]
Estimated environmental costs			64,700,000
Various Environmental Matters | Maximum
Site Contingency [Line Items]
Estimated environmental costs			453,800,000
Various Environmental Matters | Maximum | Sacramento, California
Site Contingency [Line Items]
Estimated environmental costs			347,700,000
Guarantee obligations		$ 75,000,000
Various Environmental Matters | Maximum | Baldwin Park Operable Unit
Site Contingency [Line Items]
Estimated environmental costs			$ 78,000,000