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Revenue Recognition (Tables) | 12 Months Ended
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Dec. 31, 2020
Revenue from Contract with Customer [Abstract] |
Disaggregation of Revenue | The table below reconciles revenue disaggregation by customer class to segment revenue as well as to revenues reflected on the Statements of Consolidated Income (Loss):
Year Ended December 31, 2020 (in millions) | Gas Distribution Operations |  | Electric Operations |  | Corporate and Other(2) |  | Total
Customer Revenues(1) |  |  |  |  |  |  |
Residential | $ | 2,075.0 |  |  | $ | 527.8 |  |  | $ | — |  |  | $ | 2,602.8 |
Commercial | 670.5 |  |  | 480.3 |  |  | — |  |  | 1,150.8 |
Industrial | 212.8 |  |  | 412.1 |  |  | — |  |  | 624.9 |
Off-system | 41.0 |  |  | — |  |  | — |  |  | 41.0 |
Miscellaneous | 32.7 |  |  | 20.2 |  |  | 0.8 |  |  | 53.7 |
Total Customer Revenues | $ | 3,032.0 |  |  | $ | 1,440.4 |  |  | $ | 0.8 |  |  | $ | 4,473.2 |
Other Revenues | 96.1 |  |  | 95.5 |  |  | 16.9 |  |  | 208.5 |
Total Operating Revenues | $ | 3,128.1 |  |  | $ | 1,535.9 |  |  | $ | 17.7 |  |  | $ | 4,681.7 |
(1)Customer revenue amounts exclude intersegment revenues. See Note 24, "Segments of Business," for discussion of intersegment revenues. (2)Other revenues related to the Transition Services Agreement entered into in connection with the sale of the Massachusetts Business.
Year Ended December 31, 2019 (in millions) | Gas Distribution Operations |  | Electric Operations |  | Corporate and Other |  | Total
Customer Revenues(1) |  |  |  |  |  |  |
Residential | $ | 2,309.0 |  |  | $ | 481.6 |  |  | $ | — |  |  | $ | 2,790.6 |
Commercial | 771.3 |  |  | 486.6 |  |  | — |  |  | 1,257.9 |
Industrial | 245.2 |  |  | 607.7 |  |  | — |  |  | 852.9 |
Off-system | 77.7 |  |  | — |  |  | — |  |  | 77.7 |
Miscellaneous | 52.0 |  |  | 21.5 |  |  | 0.8 |  |  | 74.3 |
Total Customer Revenues | $ | 3,455.2 |  |  | $ | 1,597.4 |  |  | $ | 0.8 |  |  | $ | 5,053.4 |
Other Revenues | 54.5 |  |  | 101.0 |  |  | — |  |  | 155.5 |
Total Operating Revenues | $ | 3,509.7 |  |  | $ | 1,698.4 |  |  | $ | 0.8 |  |  | $ | 5,208.9 |
(1)Customer revenue amounts exclude intersegment revenues. See Note 24, "Segments of Business," for discussion of intersegment revenues.
Year Ended December 31, 2018 (in millions) | Gas Distribution Operations |  | Electric Operations |  | Corporate and Other |  | Total
Customer Revenues(1) |  |  |  |  |  |  |
Residential | $ | 2,250.0 |  |  | $ | 494.7 |  |  | $ | — |  |  | $ | 2,744.7 |
Commercial | 751.9 |  |  | 492.7 |  |  | — |  |  | 1,244.6 |
Industrial | 228.0 |  |  | 613.6 |  |  | — |  |  | 841.6 |
Off-system | 92.4 |  |  | — |  |  | — |  |  | 92.4 |
Miscellaneous | 49.7 |  |  | 17.4 |  |  | 0.7 |  |  | 67.8 |
Total Customer Revenues | $ | 3,372.0 |  |  | $ | 1,618.4 |  |  | $ | 0.7 |  |  | $ | 4,991.1 |
Other Revenues | 34.4 |  |  | 89.0 |  |  | — |  |  | 123.4 |
Total Operating Revenues | $ | 3,406.4 |  |  | $ | 1,707.4 |  |  | $ | 0.7 |  |  | $ | 5,114.5 |
(1)Customer revenue amounts exclude intersegment revenues. See Note 24, "Segments of Business," for discussion of intersegment revenues.
Customer Accounts Receivable | The opening and closing balances of customer receivables for the years ended December 31, 2020 and 2019 are presented in the table below. We had no significant contract assets or liabilities during the period. Additionally, we have not incurred any significant costs to obtain or fulfill contracts.
(in millions) | Customer Accounts Receivable, Billed (less reserve)(1) |  | Customer Accounts Receivable, Unbilled (less reserve) |
Balance as of December 31, 2019 | $ | 466.6 |  |  | $ | 346.6 |  |
Balance as of December 31, 2020 | 400.0 |  |  | 327.2 |  |
Decrease | $ | (66.6) |  |  | $ | (19.4) |  |
(1)Customer billed receivables decreased due to decreased natural gas costs and warmer weather in 2020 compared to 2019.
Financing Receivable, Allowance for Credit Loss | A rollforward of our allowance for credit losses for the year ended December 31, 2020 are presented in the table below:
Year Ended December 31, 2020 (in millions) | Gas Distribution Operations |  | Electric Operations |  | Corporate and Other |  | Total
Beginning balance(1) | 9.1 |  |  | 3.1 |  |  | 0.8 |  |  | 13.0 |
Current period provisions | 45.3 |  |  | 9.3 |  |  | — |  |  | 54.6 |
Write-offs charged against allowance | (26.7) |  |  | (3.0) |  |  | — |  |  | (29.7) |
Recoveries of amounts previously written off | 14.1 |  |  | 0.3 |  |  | — |  |  | 14.4 |
Ending balance of the allowance for credit losses | 41.8 |  |  | 9.7 |  |  | 0.8 |  |  | 52.3 |
(1)Total beginning balance differs from that presented in the Consolidated Balance Sheets as it excludes Columbia of Massachusetts. Columbia of Massachusetts' customer receivables and related allowance for credit losses were included in the sale of the Massachusetts Business that occurred on October 9, 2020.

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