Asset Retirement Obligations (Details) - ARIZONA PUBLIC SERVICE COMPANY - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligations
Newly incurred or acquired obligations	$ 17,864	$ 0
ARO, decrease	1,000
Change in asset retirement obligations
Asset retirement obligations at the beginning of year	679,529	624,475
Changes attributable to:
Accretion expense	36,876	33,104
Settlements	(9,726)	0
Estimated cash flow revisions	2,002	21,950
Newly incurred or acquired obligations	17,864	0
Asset retirement obligations at the end of year	726,545	679,529
Solar Panels
Asset Retirement Obligations
Newly incurred or acquired obligations	14,000
Changes attributable to:
Newly incurred or acquired obligations	14,000
4CA
Asset Retirement Obligations
ARO, decrease	9,000
Navajo Generating Station
Asset Retirement Obligations
Newly incurred or acquired obligations		22,000
Increase in regulatory asset		2,000
Decrease in regulatory liability		20,000
Changes attributable to:
Newly incurred or acquired obligations		$ 22,000
Consumer Solar Panels
Asset Retirement Obligations
Newly incurred or acquired obligations	7,000
Changes attributable to:
Newly incurred or acquired obligations	$ 7,000