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Commitments and Contingencies - Environmental Matters and Financial Assurances (Details) - USD ($) $ in Thousands				12 Months Ended
	Feb. 22, 2021	Jul. 03, 2018	Jul. 06, 2016	Dec. 31, 2020
Financial Assurances
Equity contribution guarantees				$ 3,000
Production tax credit guarantees				39,000
2017 Settlement Agreement and its Customer Education and Outreach Plan \| ARIZONA PUBLIC SERVICE COMPANY \| Subsequent Event
Arizona Attorney General [Abstract]
Settlement amount	$ 24,750
Settlement amount returned to customers	$ 24,000
Letter of credit \| ARIZONA PUBLIC SERVICE COMPANY
Financial Assurances
Outstanding letters of credit				5,200
Four Corners \| NTEC
Environmental Matters
Option to purchase, ownership interest (as a percent)		7.00%	7.00%
Payment received for coal supply agreement		$ 70,000
Four Corners \| 4CA
Environmental Matters
Percentage share cost of control			7.00%
Remaining balance of notes				27,000
Four Corners \| Coal Supply Agreement Arbitration \| NTEC
Environmental Matters
Option to purchase, ownership interest (as a percent)			7.00%
Four Corners \| Coal Supply Agreement Arbitration \| 4CA
Environmental Matters
Asset purchase agreement				$ 10,000
Regional Haze Rules \| Four Corners Units 4 and 5 \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Percentage share cost of control				63.00%
Expected environmental cost				$ 400,000
Regional Haze Rules \| Four Corners Units 4 and 5 \| Four Corners \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				$ 45,000
Regional Haze Rules \| Four Corners Units 4 and 5 \| Natural Gas Tolling Letter of Credit \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional percentage share of cost of control				7.00%
Coal Combustion Waste \| Four Corners \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				$ 27,000
Coal Combustion Waste \| Navajo Generating Station \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				1,000
Coal Combustion Waste \| Minimum \| Cholla \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				16,000
Coal Combustion Waste \| Minimum \| Cholla and Four Corners \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				10,000
Coal Combustion Waste \| Maximum \| Cholla and Four Corners \| ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters
Additional expected environment cost				15,000
Surety Bonds Expiring in 2020 \| ARIZONA PUBLIC SERVICE COMPANY
Financial Assurances
Surety bonds expiring, amount				$ 16,000