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Schedule II - Valuation and Qualifying Accounts | 12 Months Ended
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Dec. 31, 2018
Valuation and Qualifying Accounts [Abstract] |
Valuation and Qualifying Accounts | Exelon Corporation and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 322 |  |  | $ | 159 |  |  | $ | 35 |  | (c) | $ | 197 |  | (e) | $ | 319 |
Deferred tax valuation allowance |  | 37 |  |  | — |  |  | 5 |  |  | 7 |  |  | 35 |
Reserve for obsolete materials |  | 174 |  |  | 25 |  |  | (31 | ) | (d) | 12 |  |  | 156 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 334 |  |  | $ | 126 |  |  | $ | 27 |  | (c) | $ | 165 |  | (e) | $ | 322 |
Deferred tax valuation allowance |  | 20 |  |  | — |  |  | 17 |  |  | — |  |  | 37 |
Reserve for obsolete materials |  | 113 |  |  | 56 |  |  | 10 |  |  | 5 |  |  | 174 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 284 |  |  | $ | 162 |  |  | $ | 99 |  | (b)(c) | $ | 211 |  | (e) | $ | 334 |
Deferred tax valuation allowance |  | 13 |  |  | — |  |  | 10 |  | (b) | 3 |  |  | 20 |
Reserve for obsolete materials |  | 105 |  |  | 12 |  |  | 1 |  | (b) | 5 |  |  | 113 |
__________
(a) | Excludes the non-current allowance for uncollectible accounts related to PECO’s installment plan receivables of $13 million, $15 million, and $23 million for the years ended December 31, 2018, 2017 and 2016, respectively.
(b) | Primarily represents the addition of PHI's results as of March 23, 2016, the date of the merger
(c) | Includes charges for late payments and non-service receivables.
(d) | Primarily reflects the reclassification of assets as held for sale.
(e) | Write-off of individual accounts receivable.
Exelon Generation Company, LLC and Subsidiary Companies (2) Generation
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Exelon Generation Company, LLC and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 114 |  |  | $ | 44 |  |  | $ | 4 |  |  | $ | 58 |  |  | $ | 104 |
Deferred tax valuation allowance |  | 23 |  |  | — |  |  | 3 |  |  | — |  |  | 26 |
Reserve for obsolete materials |  | 166 |  |  | 20 |  |  | (32 | ) | (a) | 9 |  |  | 145 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 91 |  |  | $ | 34 |  |  | $ | — |  |  | $ | 11 |  |  | $ | 114 |
Deferred tax valuation allowance |  | 9 |  |  | — |  |  | 14 |  |  | — |  |  | 23 |
Reserve for obsolete materials |  | 106 |  |  | 51 |  |  | 9 |  |  | — |  |  | 166 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 77 |  |  | $ | 19 |  |  | $ | 3 |  |  | $ | 8 |  |  | $ | 91 |
Deferred tax valuation allowance |  | 11 |  |  | — |  |  | — |  |  | 2 |  |  | 9 |
Reserve for obsolete materials |  | 102 |  |  | 6 |  |  | — |  |  | 2 |  |  | 106 |
__________
(a) | Primarily reflects the reclassification of assets as held for sale.
Commonwealth Edison Company and Subsidiary Companies (3) ComEd
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Shareholders’ Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Commonwealth Edison Company and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 73 |  |  | $ | 44 |  |  | $ | 23 |  | (a) | $ | 59 |  | (b) | $ | 81 |
Reserve for obsolete materials |  | 5 |  |  | 3 |  |  | 1 |  |  | 3 |  |  | 6 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 70 |  |  | $ | 39 |  |  | $ | 20 |  | (a) | $ | 56 |  | (b) | $ | 73 |
Reserve for obsolete materials |  | 4 |  |  | 3 |  |  | 1 |  |  | 3 |  |  | 5 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 75 |  |  | $ | 45 |  |  | $ | 23 |  | (a) | $ | 73 |  | (b) | $ | 70 |
Reserve for obsolete materials |  | 3 |  |  | 4 |  |  | 1 |  |  | 4 |  |  | 4 |
__________
(a) | Primarily charges for late payments and non-service receivables.
(b) | Write-off of individual accounts receivable.
PECO Energy Company and Subsidiary Companies (4) PECO
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Shareholder's Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
PECO Energy Company and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 56 |  |  | $ | 33 |  |  | $ | 3 |  | (b) | $ | 31 |  | (c) | $ | 61 |
Reserve for obsolete materials |  | 2 |  |  | — |  |  | — |  |  | — |  |  | 2 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 61 |  |  | $ | 26 |  |  | $ | 4 |  | (b) | $ | 35 |  | (c) | $ | 56 |
Reserve for obsolete materials |  | 2 |  |  | — |  |  | — |  |  | — |  |  | 2 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts(a) |  | $ | 83 |  |  | $ | 32 |  |  | $ | 7 |  | (b) | $ | 61 |  | (c) | $ | 61 |
Reserve for obsolete materials |  | 1 |  |  | 1 |  |  | — |  |  | — |  |  | 2 |
__________
(a) | Excludes the non-current allowance for uncollectible accounts related to PECO’s installment plan receivables of $13 million, $15 million, and $23 million for the years ended December 31, 2018, 2017, and 2016, respectively.
(b) | Primarily charges for late payments.
(c) | Write-off of individual accounts receivable.
Baltimore Gas and Electric Company and Subsidiary Companies (5) BGE
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Shareholder's Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Baltimore Gas and Electric Company and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 24 |  |  | $ | 10 |  |  | $ | (2 | ) |  | $ | 12 |  | (a) | $ | 20 |
Deferred tax valuation allowance |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
Reserve for obsolete materials |  | — |  |  | 1 |  |  | — |  |  | — |  |  | 1 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 32 |  |  | $ | 8 |  |  | $ | (3 | ) |  | $ | 13 |  | (a) | $ | 24 |
Deferred tax valuation allowance |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
Reserve for obsolete materials |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 49 |  |  | $ | 1 |  |  | $ | 9 |  |  | $ | 27 |  | (a) | $ | 32 |
Deferred tax valuation allowance |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
Reserve for obsolete materials |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
__________
(a) | Write-off of individual accounts receivable.
Pepco Holdings LLC and Subsidiary Companies (6) PHI
(i) |  | Successor Company Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income (Loss) for the Years Ended December 31, 2018 and 2017 and for the Period March 24, 2016 to December 31, 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018 and 2017 and for the Period March 24, 2016 to December 31, 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Equity for the Years Ended December 31, 2018 and 2017 and for the Period March 24, 2016 to December 31, 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Predecessor Company Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 13, 2017 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income for the Period January 1, 2016 to March 23, 2016
|  | Consolidated Statements of Cash Flows for the Period January 1, 2016 to March 23, 2016
|  | Consolidated Statements of Changes in Equity for the Period January 1, 2016 to March 23, 2016
|  | Notes to Consolidated Financial Statements
(iii) |  | Successor Financial Statement Schedule:
|  | Schedule II – Valuation and Qualifying Accounts - For the Years Ended December 31, 2018 and 2017 and the Period March 24, 2016 to December 31, 2016
(iv) |  | Predecessor Financial Statement Schedule:
|  | Schedule II – Valuation and Qualifying Accounts - For the Period January 1, 2016 to March 23, 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Pepco Holdings LLC and Subsidiary Companies Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the Year Ended December 31, 2018 (Successor) |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 55 |  |  | $ | 28 |  |  | $ | 7 |  | (a) | $ | 37 |  | (b) | $ | 53 |
Deferred tax valuation allowance |  | 13 |  |  | — |  |  | 2 |  |  | 7 |  |  | 8 |
Reserve for obsolete materials |  | 2 |  |  | — |  |  | — |  |  | — |  |  | 2 |
For the Year Ended December 31, 2017 (Successor) |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 80 |  |  | $ | 19 |  |  | $ | 6 |  | (a) | $ | 50 |  | (b) | $ | 55 |
Deferred tax valuation allowance |  | 10 |  |  | — |  |  | 3 |  |  | — |  |  | 13 |
Reserve for obsolete materials |  | 2 |  |  | 2 |  |  | — |  |  | 2 |  |  | 2 |
March 24, 2016 to December 31, 2016 (Successor) |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 52 |  |  | $ | 65 |  |  | $ | 5 |  | (a) | $ | 42 |  | (b) | $ | 80 |
Deferred tax valuation allowance |  | 63 |  |  | — |  |  | (53 | ) |  | — |  |  | 10 |
Reserve for obsolete materials |  | — |  |  | 1 |  |  | — |  |  | (1 | ) |  | 2 |
January 1, 2016 to March 23, 2016 (Predecessor) |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 56 |  |  | $ | 16 |  |  | $ | 2 |  | (a) | $ | 22 |  | (b) | $ | 52 |
Deferred tax valuation allowance |  | 63 |  |  | — |  |  | — |  |  | — |  |  | 63 |
Reserve for obsolete materials |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
__________
(a) | Primarily charges for late payments.
(b) | Write-off of individual accounts receivable.
Potomac Electric Power Company (7) Pepco
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Statements of Operations and Comprehensive Income for the Years Ended December 31, 2018, 2017 and 2016
|  | Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Balance Sheets at December 31, 2018 and 2017
|  | Statements of Changes in Shareholder's Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Potomac Electric Power Company Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 21 |  |  | $ | 11 |  |  | $ | 3 |  | (a) | $ | 14 |  | (b) | $ | 21 |
Reserve for obsolete materials |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 29 |  |  | $ | 8 |  |  | $ | 2 |  | (a) | $ | 18 |  | (b) | $ | 21 |
Reserve for obsolete materials |  | 1 |  |  | 1 |  |  | — |  |  | 1 |  |  | 1 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 17 |  |  | $ | 29 |  |  | $ | 3 |  | (a) | $ | 20 |  | (b) | $ | 29 |
Reserve for obsolete materials |  | — |  |  | 3 |  |  | — |  |  | 2 |  |  | 1 |
__________
(a) | Primarily charges for late payments.
(b) | Write-off of individual accounts receivable.
Delmarva Power & Light Company (8) DPL
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Statements of Operations and Comprehensive Income (Loss) for the Years Ended December 31, 2018, 2017 and 2016
|  | Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Balance Sheets at December 31, 2018 and 2017
|  | Statements of Changes in Shareholder's Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Delmarva Power & Light Company Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 16 |  |  | $ | 6 |  |  | $ | 2 |  | (a) | $ | 11 |  | (b) | $ | 13 |
Reserve for obsolete materials |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 24 |  |  | $ | 3 |  |  | $ | 2 |  | (a) | $ | 13 |  | (b) | $ | 16 |
Reserve for obsolete materials |  | — |  |  | 1 |  |  | — |  |  | 1 |  |  | — |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 17 |  |  | $ | 23 |  |  | $ | 2 |  | (a) | $ | 18 |  | (b) | $ | 24 |
Reserve for obsolete materials |  | — |  |  | 1 |  |  | — |  |  | 1 |  |  | — |
__________
(a) | Primarily charges for late payments.
(b) | Write-off of individual accounts receivable.
Atlantic City Electric Company and Subsidiary Company (9) ACE
(i) |  | Financial Statements (Item 8):
|  | Report of Independent Registered Public Accounting Firm dated February 8, 2019 of PricewaterhouseCoopers LLP
|  | Consolidated Statements of Operations and Comprehensive Income (Loss) for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Statements of Cash Flows for the Years Ended December 31, 2018, 2017 and 2016
|  | Consolidated Balance Sheets at December 31, 2018 and 2017
|  | Consolidated Statements of Changes in Shareholder's Equity for the Years Ended December 31, 2018, 2017 and 2016
|  | Notes to Consolidated Financial Statements
(ii) |  | Financial Statement Schedule:
|  | Schedule II—Valuation and Qualifying Accounts for the Years Ended December 31, 2018, 2017 and 2016
|  | Schedules not included are omitted because of the absence of conditions under which they are required or because the required information is provided in the consolidated financial statements, including the notes thereto
Atlantic City Electric Company and Subsidiary Company Schedule II – Valuation and Qualifying Accounts
Column A |  | Column B |  | Column C |  | Column D |  | Column E
|  |  |  | Additions and adjustments |  |  |  |
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  | Charged to Other Accounts |  | Deductions |  | Balance at End of Period
|  | (in millions)
For the year ended December 31, 2018 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 18 |  |  | $ | 11 |  |  | $ | 2 |  | (a) | $ | 12 |  | (b) | $ | 19 |
Reserve for obsolete materials |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
For the year ended December 31, 2017 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 27 |  |  | $ | 8 |  |  | $ | 2 |  | (a) | $ | 19 |  | (b) | $ | 18 |
Reserve for obsolete materials |  | 1 |  |  | — |  |  | — |  |  | — |  |  | 1 |
For the year ended December 31, 2016 |  |  |  |  |  |  |  |  |  |
Allowance for uncollectible accounts |  | $ | 17 |  |  | $ | 32 |  |  | $ | 2 |  | (a) | $ | 24 |  | (b) | $ | 27 |
Reserve for obsolete materials |  | — |  |  | 1 |  |  | — |  |  | — |  |  | 1 |
__________
(a) | Primarily charges for late payments.
(b) | Write-off of individual accounts receivable.

X
- Definition The entire disclosure for any allowance and reserve accounts (their beginning and ending balances, as well as a reconciliation by type of activity during the period). Alternatively, disclosure of the required information may be within the footnotes to the financial statements or a supplemental schedule to the financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -URI http://asc.fasb.org/topic&trid=2122369 + Details
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- References No definition available. + Details
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