Summary of Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Income taxes, net of refunds	$ 12,535	$ 21,173	$ 2,186
Interest, net of amounts capitalized	218,664	208,479	189,288
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Accrued capital expenditures	141,297	132,620	130,404
Dividends declared but not paid	87,982	82,675	77,667
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	11,262	0	0
Sale of 4CA 7% interest in Four Corners	0	68,907	0
ARIZONA PUBLIC SERVICE COMPANY
Cash and Cash Equivalents [Line Items]
Income taxes, net of refunds	(15,042)	77,942	(14,098)
Interest, net of amounts capitalized	204,261	196,419	184,210
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Accrued capital expenditures	141,297	132,620	130,057
Dividends declared but not paid	88,000	82,700	77,700
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	$ 11,262	$ 0	$ 0