Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 341	$ 316	$ 286
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	372	350	328
Deferred income taxes and investment tax credits	(1)	192	87
Allowance for equity funds used during construction	(10)	(2)	(24)
Deferred recovery clauses	(55)	(83)	54
Receivables, less allowance for uncollectibles	(2)	(43)	18
Inventories	4	13	16
Taxes accrued	6	(9)	68
Accounts payable	11	(16)	63
Regulatory assets and liabilities	98	(100)	(11)
Other	38	(6)	(54)
Cash flows from operating activities	802	612	831
Cash flows used in investing activities
Capital expenditures	(1,109)	(640)	(727)
Net proceeds from sale of assets	1	0	9
Cash flows used in investing activities	(1,108)	(640)	(718)
Cash flows from or used in financing activities
Equity contributions from TECO Energy	345	190
Proceeds from long-term debt issuance	714	0	0
Repayment of long-term debt	(304)	0	(83)
Net change in short-term debt (maturities of 90 days or less)	216	(165)	109
Proceeds from other short-term debt (maturities over 90 days)	0	300	0
Repayment of other short-term debt (maturities over 90 days)	(300)	0	0
Dividends to TECO Energy	(362)	(292)
Other financing activities	(1)	(2)	1
Cash flows from/(used in) financing activities	308	31	(112)
Net increase in cash and cash equivalents	2	3	1
Cash and cash equivalents at beginning of the year	13	10	9
Cash and cash equivalents at end of the year	15	13	10
Supplemental disclosure of cash paid (received):
Interest	112	115	103
Income taxes	77	13	(3)
Supplemental disclosure of non-cash activities
Change in accrued capital expenditures	40	(16)	(9)
TECO Energy [Member]
Cash flows from or used in financing activities
Equity contributions from TECO Energy	345	190	150
Dividends to TECO Energy	$ (362)	$ (292)	$ (289)