Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	$ 43,435	$ 40,731	$ 41,966
Additions for tax positions of the current year	3,418	3,373	3,436
Additions for tax positions of prior years	1,431	1,843	2,696
Reductions for tax positions of prior years for:
Changes in judgment	(1,965)	(2,078)	(1,764)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	(664)	(434)	(5,603)
Total unrecognized tax benefits, end of the year	45,655	43,435	40,731
ARIZONA PUBLIC SERVICE COMPANY
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	43,435	40,731	41,966
Additions for tax positions of the current year	3,418	3,373	3,436
Additions for tax positions of prior years	1,431	1,843	2,696
Reductions for tax positions of prior years for:
Changes in judgment	(1,965)	(2,078)	(1,764)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	(664)	(434)	(5,603)
Total unrecognized tax benefits, end of the year	$ 45,655	$ 43,435	$ 40,731