Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income	$ 424	$ 370	$ 341
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	384	377	372
Deferred income taxes and investment tax credits	54	15	(1)
Allowance for equity funds used during construction	(30)	(11)	(10)
Deferred recovery clauses	(40)	63	(55)
Receivables, less allowance for credit losses	(10)	52	(2)
Inventories	7	6	4
Taxes accrued	23	1	6
Accounts payable	34	(4)	11
Regulatory assets and liabilities	(18)	1	98
Other	1	(29)	38
Cash flows from operating activities	829	841	802
Cash flows used in investing activities
Capital expenditures	(1,361)	(1,283)	(1,109)
Net proceeds from sale of assets	6	0	1
Cash flows used in investing activities	(1,355)	(1,283)	(1,108)
Cash flows from or used in financing activities
Proceeds from long-term debt issuance	0	292	714
Repayment of long-term debt	0	0	(304)
Net change in short-term debt (maturities of 90 days or less)	127	127	216
Proceeds from other short-term debt (maturities over 90 days)	300	0	0
Repayment of other short-term debt (maturities over 90 days)	0	0	(300)
Other financing activities	(2)	0	(1)
Cash flows from financing activities	522	441	308
Net increase (decrease) in cash and cash equivalents	(4)	(1)	2
Cash and cash equivalents at beginning of the year	14	15	13
Cash and cash equivalents at end of the year	10	14	15
Supplemental disclosure of cash paid (received):
Interest	126	134	112
Income taxes	14	63	77
Supplemental disclosure of non-cash activities
Change in accrued capital expenditures	1	17	40
TECO Energy [Member]
Cash flows from or used in financing activities
Equity contributions from TECO Energy	505	395	345
Dividends to TECO Energy	$ (408)	$ (373)	$ (362)