CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 15,440	$ 13,892
Customer and other receivables	212,188	305,147
Accrued unbilled revenues	118,989	112,434
Allowance for doubtful accounts	(2,046)	(2,513)
Materials and supplies (at average cost)	257,815	264,012
Fossil fuel (at average cost)	48,062	25,258
Assets from risk management activities (Note 7)	1,994	1,931
Deferred fuel and purchased power regulatory asset (Note 4)	74,585	75,637
Other regulatory assets (Note 4)	178,490	172,451
Other current assets	51,887	48,039
Total current assets	957,404	1,016,288
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Note 12)	861,439	871,000
Other special use funds (Note 12)	217,992	32,542
Other assets	58,177	52,040
Total investments and other assets	1,137,608	955,582
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	17,896,772	17,798,061
Accumulated depreciation and amortization	(6,231,918)	(6,128,535)
Net	11,664,854	11,669,526
Construction work in progress	1,453,610	1,291,498
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	108,678	109,645
Intangible assets, net of accumulated amortization	262,523	257,189
Nuclear fuel, net of accumulated amortization	135,400	117,408
Total property, plant and equipment	13,625,065	13,445,266
DEFERRED DEBITS
Regulatory assets (Note 4)	1,200,260	1,202,302
Assets for other postretirement benefits (Note 5)	89,378	268,978
Other	138,591	130,666
Total deferred debits	1,428,229	1,601,946
TOTAL ASSETS	17,148,306	17,019,082
CURRENT LIABILITIES
Accounts payable	205,169	256,442
Accrued taxes	194,930	148,946
Accrued interest	51,335	56,397
Common dividends payable	0	77,667
Short-term borrowings (Note 3)	369,900	95,400
Current maturities of long-term debt (Note 3)	582,000	82,000
Customer deposits	75,759	70,388
Liabilities from risk management activities (Note 7)	67,743	59,252
Liabilities for asset retirements	6,397	4,745
Regulatory liabilities (Note 4)	136,535	100,086
Other current liabilities	184,623	246,529
Total current liabilities	1,874,391	1,197,852
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 3)	4,290,533	4,789,713
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,689,601	1,690,805
Regulatory liabilities (Note 4)	2,415,417	2,452,536
Liabilities for asset retirements	677,629	674,784
Liabilities for pension benefits (Note 5)	284,007	327,300
Liabilities from risk management activities (Note 7)	47,626	37,170
Customer advances	109,629	113,996
Coal mine reclamation	231,512	231,597
Deferred investment tax credit	205,428	205,575
Unrecognized tax benefits	13,229	13,115
Other	155,633	148,909
Total deferred credits and other	5,829,711	5,895,787
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 111,961,963 and 111,816,170 issued at respective dates	2,620,261	2,614,805
Treasury stock at cost; 29,097 and 64,463 shares at respective dates	(2,431)	(5,624)
Total common stock	2,617,830	2,609,181
Retained earnings	2,454,268	2,442,511
Accumulated other comprehensive loss	(52,341)	(45,002)
Total shareholders’ equity	5,019,757	5,006,690
Noncontrolling interests (Note 6)	133,914	129,040
Total equity	5,153,671	5,135,730
TOTAL LIABILITIES AND EQUITY	17,148,306	17,019,082
Arizona Public Service Company
CURRENT ASSETS
Cash and cash equivalents	14,001	13,851
Customer and other receivables	198,703	292,791
Accrued unbilled revenues	118,989	112,434
Allowance for doubtful accounts	(2,046)	(2,513)
Materials and supplies (at average cost)	256,573	262,630
Fossil fuel (at average cost)	48,062	25,258
Assets from risk management activities (Note 7)	1,994	1,931
Deferred fuel and purchased power regulatory asset (Note 4)	74,585	75,637
Other regulatory assets (Note 4)	178,490	172,451
Other current assets	45,477	41,055
Total current assets	934,828	995,525
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Note 12)	861,439	871,000
Other special use funds (Note 12)	215,800	30,358
Other assets	41,019	36,796
Total investments and other assets	1,118,258	938,154
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	17,751,964	17,654,078
Accumulated depreciation and amortization	(6,144,874)	(6,041,965)
Net	11,607,090	11,612,113
Construction work in progress	1,424,023	1,266,636
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	108,678	109,645
Intangible assets, net of accumulated amortization	262,363	257,028
Nuclear fuel, net of accumulated amortization	135,400	117,408
Total property, plant and equipment	13,537,554	13,362,830
DEFERRED DEBITS
Regulatory assets (Note 4)	1,200,260	1,202,302
Assets for other postretirement benefits (Note 5)	85,515	265,139
Other	132,336	129,801
Total deferred debits	1,418,111	1,597,242
TOTAL ASSETS	17,008,751	16,893,751
CURRENT LIABILITIES
Accounts payable	198,025	247,852
Accrued taxes	211,455	157,349
Accrued interest	48,828	55,533
Common dividends payable	0	77,700
Short-term borrowings (Note 3)	255,500	0
Current maturities of long-term debt (Note 3)	582,000	82,000
Customer deposits	75,759	70,388
Liabilities from risk management activities (Note 7)	67,743	59,252
Liabilities for asset retirements	5,898	4,192
Regulatory liabilities (Note 4)	136,535	100,086
Other current liabilities	180,005	243,922
Total current liabilities	1,761,748	1,098,274
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,741,907	1,742,485
Regulatory liabilities (Note 4)	2,415,417	2,452,536
Liabilities for asset retirements	669,247	666,527
Liabilities for pension benefits (Note 5)	263,985	306,542
Liabilities from risk management activities (Note 7)	47,626	37,170
Customer advances	109,629	113,996
Coal mine reclamation	215,615	215,830
Deferred investment tax credit	205,428	205,575
Unrecognized tax benefits	43,990	43,876
Other	140,440	133,779
Total deferred credits and other	5,853,284	5,918,316
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
EQUITY
Total common stock	178,162	178,162
Additional paid-in capital	2,571,696	2,571,696
Retained earnings	2,548,591	2,533,954
Accumulated other comprehensive loss	(30,851)	(26,983)
Total shareholders’ equity	5,267,598	5,256,829
Noncontrolling interests (Note 6)	133,914	129,040
Total equity	5,401,512	5,385,869
Long-term debt less current maturities (Note 3)	3,992,207	4,491,292
Total capitalization	9,393,719	9,877,161
TOTAL LIABILITIES AND EQUITY	$ 17,008,751	$ 16,893,751