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Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current |  | $ 294 | $ 244
Regulatory assets-noncurrent |  | 2,480 | 2,473
Total regulatory assets |  | 2,774 | 2,717
Deferred nuclear refueling outage costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [1] | 54 | 71
Deferred rate adjustment clause costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [2] | 70 | 63
Regulatory assets-noncurrent | [2] | 401 | 329
Deferred cost of fuel used in electric generation |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [3] | 23 |
Unrecovered gas costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [4] | 38 | 19
Other |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current |  | 109 | 91
Regulatory assets-noncurrent |  | 119 | 155
Unrecognized pension and other postretirement benefit costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [5] | 1,336 | 1,401
Derivatives |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [6] | 223 | 174
PJM transmission rates |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [7] | 222 | 192
Income taxes recoverable through future rates |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [8] | 32 | 123
Utility reform legislation |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [9] | $ 147 | 99
Maximum | Deferred nuclear refueling outage costs |  |  |
Regulatory Assets [Line Items] |  |  |
Amortization period for deferred costs |  | 18 months |
Virginia Electric and Power Company |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current |  | $ 205 | 179
Regulatory assets-noncurrent |  | 810 | 770
Total regulatory assets |  | 1,015 | 949
Virginia Electric and Power Company | Deferred nuclear refueling outage costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [1] | 54 | 71
Virginia Electric and Power Company | Deferred rate adjustment clause costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [2] | 56 | 51
Regulatory assets-noncurrent | [2] | 312 | 246
Virginia Electric and Power Company | Deferred cost of fuel used in electric generation |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [3] | 23 |
Virginia Electric and Power Company | Other |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current |  | 72 | 57
Regulatory assets-noncurrent |  | 86 | 123
Virginia Electric and Power Company | Derivatives |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [6] | 190 | 133
Virginia Electric and Power Company | PJM transmission rates |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [7] | 222 | 192
Virginia Electric and Power Company | Income taxes recoverable through future rates |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [8] |  | 76
Dominion Energy Gas Holdings, LLC |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [10] | 26 | 26
Regulatory assets-noncurrent |  | 511 | 577
Total regulatory assets |  | 537 | 603
Dominion Energy Gas Holdings, LLC | Deferred rate adjustment clause costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [2] | 14 | 12
Regulatory assets-noncurrent | [2] | 89 | 79
Dominion Energy Gas Holdings, LLC | Unrecovered gas costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current | [4] | 8 | 12
Dominion Energy Gas Holdings, LLC | Other |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-current |  | 4 | 2
Regulatory assets-noncurrent |  | 17 | 18
Dominion Energy Gas Holdings, LLC | Unrecognized pension and other postretirement benefit costs |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [5] | 258 | 358
Dominion Energy Gas Holdings, LLC | Income taxes recoverable through future rates |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [8] |  | 23
Dominion Energy Gas Holdings, LLC | Utility reform legislation |  |  |
Regulatory Assets [Line Items] |  |  |
Regulatory assets-noncurrent | [9] | $ 147 | $ 99
[1] | Legislation enacted in Virginia in April 2014 requires Virginia Power to defer operation and maintenance costs incurred in connection with the refueling of any nuclear-powered generating plant. These deferred costs will be amortized over the refueling cycle, not to exceed 18 months.
[2] | Primarily reflects deferrals under the electric transmission FERC formula rate and the deferral of costs associated with certain current and prospective rider projects for Virginia Power and deferrals of costs associated with certain current and prospective rider projects for Dominion Energy Gas. See Note 13 for more information.
[3] | Reflects deferred fuel expenses for the Virginia and North Carolina jurisdictions of Dominion Energy's and Virginia Power's generation operations. See Note 13 for more information.
[4] | Reflects unrecovered gas costs at regulated gas operations, which are recovered through filings with the applicable regulatory authority.
[5] | Represents unrecognized pension and other postretirement employee benefit costs expected to be recovered through future rates generally over the expected remaining service period of plan participants by certain of Dominion Energy's and Dominion Energy Gas' rate-regulated subsidiaries.
[6] | As discussed under Derivative Instruments in Note 2, for jurisdictions subject to cost-based rate regulation, changes in the fair value of derivative instruments result in the recognition of regulatory assets or regulatory liabilities as they are expected to be recovered from or refunded to customers.
[7] | Reflects amount related to the PJM transmission cost allocation matter. See Note 13 for more information.
[8] | Amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC-equity and depreciation of property, plant and equipment for which deferred income taxes were not recognized for ratemaking purposes, including amounts attributable to tax rate changes. See below for discussion of the 2017 Tax Reform Act.
[9] | Ohio legislation under House Bill 95, which became effective in September 2011. This law updates natural gas legislation by enabling gas companies to include more up-to-date cost levels when filing rate cases. It also allows gas companies to seek approval of capital expenditure plans under which gas companies can recognize carrying costs on associated capital investments placed in service and can defer the carrying costs plus depreciation and property tax expenses for recovery from ratepayers in the future.
[10] | Current regulatory assets are presented in other current assets in the Consolidated Balance Sheets of Dominion Energy Gas.

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- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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