DEBT AND CREDIT AGREEMENTS (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Schedule of long-term debt instruments

The following table presents the components of long-term debt, which includes Long-Term Debt, Net and Current Maturities of Long-Term Debt, Net on the Consolidated Balance Sheets:

			December 31,
($ in millions)	Interest Rate	Maturity Date	2021		2020
Notes
2011 Senior Notes	5.15%	2021	$	—	$	250
2012 Senior Notes (1)	3.85%	2023	150		150
2014 Senior Notes	5.00%	2044	150		150
2015 Senior Notes	3.05%	2025	300		300
2018 Senior Notes	4.85%	2048	300		300
2020 Senior Notes	4.00%	2050	350		350
2020 Senior Notes	1.50%	2030	300		300
2021 Senior Notes	3.25%	2051	325		—
Tax-Exempt Local Furnishings Bonds (2)
2012 Pima A	4.50%	2030	16		16
2013 Pima A	4.00%	2029	91		91
Tax-Exempt Pollution Control Bonds
2012 Apache A (3)	4.50%	2030	177		177
Total Long-Term Debt (4)			2,159		2,084
Less Unamortized Discount and Debt Issuance Costs			24		20
Less Current Maturities of Long-Term Debt			—		250
Total Long-Term Debt, Net			$	2,135	$	1,814

(1)The 2012 Senior Notes are callable prior to December 15, 2022, with a make-whole premium plus accrued interest. After December 15, 2022, the notes are callable at par plus accrued interest.

(2)The 2012 Pima A bonds become callable at par on or after June 1, 2022. The 2013 Pima A bonds become callable at par on or after March 1, 2023.

(3)The 2012 Apache A bonds become callable at par on or after March 1, 2022.

(4)As of December 31, 2021, all of TEP's debt is unsecured.

Schedule of maturities of long-term debt

Long-term debt matures on the following dates:

(in millions)	Long-Term Debt (1)
2022	$	—
2023	150
2024	—
2025	300
2026	—
Thereafter	1,709
Total	$	2,159

(1)Total long-term debt excludes $16 million of related unamortized debt issuance costs and $8 million of unamortized original issue discount.

Schedule of line of credit facilities

Terms are as follows:

			Sub-Limit Swingline(1)		Sub-Limit LOC						Weighted Average Interest Rate
	Capacity						Borrowed(2)		Available				Pricing(3)
($ in millions)	December 31, 2021
2021 Agreement	$	250	$	15	$	50	$	25	$	225	2.53	%	LIBOR + 1.000%	or ABR + 0.00%

(1)ABR pricing would apply to swingline loans.

(2)Includes a $10 million LOC at a rate of 1.00% per annum issued in October 2021 to replace LOCs originally issued in January 2020 pursuant to TEP taking ownership of Oso Grande under the BTA.

(3)TEP's pricing may be adjusted based on performance measured using two key performance indicators: (i) the three-year average Occupational Safety and Health Administration total recordable incident rate, excluding solely COVID-19 pandemic-related incidents; and (ii) capacity targets for owned plus firm purchased power agreement renewable generation, including energy storage.

			Sub-Limit LOC						Weighted Average Interest Rate
	Capacity				Borrowed(1)		Available				Pricing
($ in millions)	December 31, 2020
2015 Agreement	$	250	$	50	$	12	$	238	—	%	LIBOR + 1.000%	or ABR + 0.00%

(1)Included $12 million in LOCs at a rate of 1.00% per annum issued in January 2020 pursuant to TEP taking ownership of Oso Grande under the BTA.