Entity Central Index Key Document and entity information. Document And Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity Legal Entity [Axis] Entity Entity [Domain] Tampa Electric Company [Member] Affiliated Entity [Member] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Statement Of Financial Position [Abstract] Statement [Table] Statement [Table] Public Utility Public Utility [Axis] Utility Plant Utility Plant [Domain] Electric. Electric [Member] Electric [Member] Gas. Gas [Member] Gas [Member] Public Utilities Inventory Public Utilities Inventory [Axis] Public Utilities Inventory Type Public Utilities Inventory Type [Domain] Fuel [Member] Public Utilities Inventory Fuel [Member] Materials and Supplies [Member] Public Utilities Inventory Supplies [Member] Statement [Line Items] Statement [Line Items] Current assets Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Receivables, less allowance for uncollectibles Receivables Net Current Inventories, at average cost Energy Related Inventory [Abstract] Utility inventories Public Utilities Inventory Derivative assets Derivative Assets Current Taxes receivable from affiliate Income Taxes Receivable Regulatory assets Regulatory Assets Current Deferred income taxes Deferred Tax Assets Net Current Prepayments and other current assets Prepaid Expense And Other Assets Current Assets held for sale Assets Of Disposal Group Including Discontinued Operation Current Total current assets Assets Current Property, plant and equipment Property Plant And Equipment Net [Abstract] Construction work in progress Public Utilities Property Plant And Equipment Construction Work In Progress Utility plant in service, at original costs Public Utilities Property Plant And Equipment Plant In Service Accumulated depreciation Public Utilities Property Plant And Equipment Accumulated Depreciation Utility plant in service, net Public Utilities Property Plant And Equipment Net Other property Property Plant And Equipment Other Property, plant and equipment, at original costs Property Plant And Equipment Gross Accumulated depreciation Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Total property, plant and equipment, net Property Plant And Equipment Net Other assets Other Assets Noncurrent [Abstract] Unamortized debt expense Unamortized Debt Issuance Expense Regulatory assets Regulatory Assets Noncurrent Goodwill Goodwill Deferred charges and other assets Deferred Costs And Other Assets Assets held for sale Disposal Group Including Discontinued Operation Assets Noncurrent Total other assets Other Assets Total assets Assets Allowance for uncollectibles Allowance For Doubtful Accounts Receivable Current Common equity, shares authorized Common Stock Shares Authorized Common equity, par value Common Stock Par Or Stated Value Per Share Common equity, shares outstanding Common Stock Shares Outstanding Current liabilities Liabilities Current [Abstract] Long-term debt due within one year Long Term Debt Current Notes payable Notes Payable Current Accounts payable Accounts Payable Current Customer deposits Customer Deposits Current Regulatory liabilities Regulatory Liability Current Derivative liabilities Derivative Liabilities Current Interest accrued Interest Payable Current Taxes accrued Accrued Income Taxes Current Other Other Liabilities Current Liabilities associated with assets held for sale Liabilities Of Disposal Group Including Discontinued Operation Current Total current liabilities Liabilities Current Other liabilities Other Liabilities Noncurrent [Abstract] Deferred income taxes Deferred Tax Liabilities Noncurrent Investment tax credits Accumulated Deferred Investment Tax Credit Regulatory liabilities Regulatory Liability Noncurrent Derivative liabilities Derivative Liabilities Noncurrent Deferred credits and other liabilities Deferred Credits And Other Liabilities Noncurrent Liabilities associated with assets held for sale Liabilities Of Disposal Group Including Discontinued Operation Noncurrent Long-term debt, less amount due within one year Long Term Debt Noncurrent Total other liabilities Liabilities Noncurrent Commitments and contingencies (see Note 10) Commitments And Contingencies Capital Stockholders Equity [Abstract] Common equity Common Stock Value Additional paid in capital Additional Paid In Capital Common Stock Retained earnings Retained Earnings Accumulated Deficit Accumulated other comprehensive loss Accumulated Other Comprehensive Income Loss Net Of Tax Total capital Stockholders Equity Total liabilities and capital Liabilities And Stockholders Equity Income Statement [Abstract] Revenues Revenues [Abstract] Regulated electric and gas Regulated Operating Revenue Unregulated Unregulated Operating Revenue Total revenues Revenues Expenses Costs And Expenses [Abstract] Fuel Fuel Costs Purchased power Cost Of Purchased Power Cost of natural gas sold Cost Of Goods Sold Oil And Gas Other Other Cost And Expense Operating Operations and maintenance other expense Operating Expenses Depreciation and amortization Depreciation And Amortization Taxes, other than income Taxes Excluding Income And Excise Taxes Total expenses Costs And Expenses Income from operations Operating Income Loss Other income Nonoperating Income Expense [Abstract] Allowance for other funds used during construction Public Utilities Allowance For Funds Used During Construction Additions Other income, net Other Nonoperating Income Expense Total other income Nonoperating Income Expense Interest charges Interest Expense [Abstract] Interest expense Interest Expense Debt Allowance for borrowed funds used during construction Public Utilities Allowance For Funds Used During Construction Capitalized Interest Total interest charges Interest Expense Income from continuing operations before provision for income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Provision for income taxes Income Tax Expense Benefit Net income from continuing operations Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest Discontinued operations Income Loss From Discontinued Operations Net Of Tax [Abstract] Loss from discontinued operations Discontinued Operation Income Loss From Discontinued Operation Before Income Tax Benefit from income taxes Discontinued Operation Tax Effect Of Discontinued Operation Loss on discontinued operations, net Income Loss From Discontinued Operations Net Of Tax Net income Net Income Loss Average common shares outstanding - Basic Weighted Average Number Of Shares Outstanding Basic Average common shares outstanding - Diluted Weighted Average Number Of Diluted Shares Outstanding Earnings per share from continuing operations - Basic Income Loss From Continuing Operations Per Basic Share Earnings per share from continuing operations - Diluted Income Loss From Continuing Operations Per Diluted Share Earnings per share from discontinued operations - Basic Income Loss From Discontinued Operations Net Of Tax Per Basic Share Earnings per share from discontinued operations - Diluted Income Loss From Discontinued Operations Net Of Tax Per Diluted Share Earnings per share - Basic Earnings Per Share Basic Earnings per share - Diluted Earnings Per Share Diluted Dividends paid per common share outstanding Common Stock Dividends Per Share Cash Paid Statement Of Income And Comprehensive Income [Abstract] Net income Other comprehensive income, net of tax Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Gain on cash flow hedges Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax Amortization of unrecognized benefit costs Other Comprehensive Income Loss Amortization Adjustment From A O C I Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax Change in benefit obligation due to valuation Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Reclassification Adjustments Net Of Tax Recognized cost due to settlement Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Net Of Tax Increase in unrecognized postemployment costs Increase Decrease In Postemployment Obligations Other comprehensive income (loss), net of tax Other Comprehensive Income Loss Net Of Tax Comprehensive income Comprehensive Income Net Of Tax Depreciation and amortization including discontinued operation. Statement Of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net income to net cash from operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Depreciation and amortization Depreciation And Amortization Including Discontinued Operation Deferred income taxes and investment tax credits Deferred Income Taxes And Tax Credits Allowance for other funds used during construction Non-cash stock compensation Share Based Compensation Loss (gain) on sales of business/assets, pretax Disposal Group Not Discontinued Operation Gain Loss On Disposal Deferred recovery clauses Increase Decrease In Over Under Energy Recovery Asset impairment, pretax Asset Impairment Charges Receivables, less allowance for uncollectibles Increase Decrease In Receivables Inventories Increase Decrease In Inventories Prepayments and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Prepayments Increase Decrease In Prepaid Expense Taxes accrued Increase Decrease In Accrued Income Taxes Payable Interest accrued Increase Decrease In Interest Payable Net Accounts payable Increase Decrease In Accounts Payable Other Other Noncash Income Expense Cash flows from operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities Net Cash Provided By Used In Investing Activities [Abstract] Capital expenditures Payments To Acquire Property Plant And Equipment Allowance for other funds used during construction Allowance For Funds Used During Construction Investing Activities Purchase of NMGI, net of cash acquired Payments To Acquire Businesses Net Of Cash Acquired Other investing activities Payments For Proceeds From Other Investing Activities Cash flows used in investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities Net Cash Provided By Used In Financing Activities [Abstract] Dividends Payments Of Dividends Proceeds from the sale of common stock Proceeds From Issuance Of Common Stock Proceeds from long-term debt issuance Proceeds From Issuance Of Long Term Debt Repayment of long-term debt Repayments Of Long Term Debt Net decrease in short-term debt Proceeds From Repayments Of Short Term Debt Cash flows from financing activities Net Cash Provided By Used In Financing Activities Net increase (decrease) in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents at beginning of the period Cash and cash equivalents at end of the period Supplemental disclosure of non-cash activities Noncash Investing And Financing Items [Abstract] Debt assumed in NMGI acquisition Noncash Or Part Noncash Acquisition Debt Assumed1 Change in accrued capital expenditures Capital Expenditures Incurred But Not Yet Paid Other Other Assets Noncurrent Long-term debt Total capitalization Capitalization Longterm Debt And Equity Electric Electric Utility Revenue Gas Gas Domestic Regulated Revenue Interest on long-term debt Other Interest Interest Expense Other Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Accounting Changes And Error Corrections [Abstract] New Accounting Pronouncements New Accounting Pronouncements And Changes In Accounting Principles [Text Block] Regulated Operations [Abstract] Regulatory Public Utilities Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Compensation And Retirement Disclosure [Abstract] Employee Postretirement Benefits Pension And Other Postretirement Benefits Disclosure [Text Block] Debt Disclosure [Abstract] Short-Term Debt Short Term Debt [Text Block] Long-Term Debt Long Term Debt [Text Block] Other comprehensive income. Other Comprehensive Income [Abstract] Other Comprehensive Income Comprehensive Income Note [Text Block] Earnings Per Share [Abstract]