Derivative Instruments and Hedging Activities - Schedule of Notional Amounts (Details) € in Millions, kWh in Millions, gal in Millions, DTH in Millions, $ in Millions	Dec. 31, 2021 USD ($) DTH kWh gal	Dec. 31, 2021 EUR (€) DTH kWh gal	Sep. 30, 2021 USD ($) gal DTH kWh	Sep. 30, 2021 EUR (€) gal DTH kWh	Dec. 31, 2020 USD ($) DTH kWh gal	Dec. 31, 2020 EUR (€) DTH kWh gal
Commodity contracts | Regulated Utility Operations | Natural Gas
Derivative [Line Items]
Notional amount (in units)	14	14	20	20	16	16
Commodity contracts | Non-utility Operations | LPG
Derivative [Line Items]
Notional amount (in units) | gal	732	732	708	708	719	719
Commodity contracts | Non-utility Operations | Electricity
Derivative [Line Items]
Notional amount (in units) | kWh	4,261	4,261	4,302	4,302	4,816	4,816
Natural gas futures, forward and pipeline contracts (in dekatherms) | Non-utility Operations | Natural Gas
Derivative [Line Items]
Notional amount (in units)	382	382	355	355	342	342
Interest rate swaps
Derivative [Line Items]
Notional amount	$ 1,418	€ 300	$ 1,421	€ 300	$ 1,306	€ 300
Forward foreign currency exchange contracts
Derivative [Line Items]
Notional amount	$ 415	€ 486	$ 509	€ 173	$ 457	€ 173