Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal									$ 18,375	$ 11,624	$ 8,630
State									3,342	3,052	1,259
Total current									21,717	14,676	9,889
Deferred:
Federal									94,721	223,729	201,743
State									17,464	19,867	24,779
Total deferred									112,185	243,596	226,522
Income tax expense	$ 6,795	$ 84,333	$ 44,039	$ (1,265)	$ 20,775	$ 144,319	$ 88,967	$ 4,211	133,902	258,272	236,411
ARIZONA PUBLIC SERVICE COMPANY
Current:
Federal									88,180	21,512	711
State									1,877	2,778	4,276
Total current									90,057	24,290	4,987
Deferred:
Federal									32,436	221,078	215,178
State									22,321	23,800	25,677
Total deferred									54,757	244,878	240,855
Income tax expense									$ 144,814	$ 269,168	$ 245,842