XML 77 R51.htm IDEA: XBRL DOCUMENT
v3.8.0.1

EMPLOYEE BENEFITPLANS (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Retirement Benefits [Abstract] |
Pension plan and other postretirement benefit plan obligations and plan assets and includes a statement of the plans funded status | The following table summarizes the changes in pension plan and other postretirement benefit plan obligations and plan assets and includes a statement of the plans’ funded status for Dominion Energy and Dominion Energy Gas (for employees represented by collective bargaining units):
|  | Pension Benefits |  |  | Other Postretirement Benefits |
Year Ended December 31, |  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
(millions, except percentages) |  |  |  |  |  |  |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Changes in benefit obligation: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligation at beginning of year |  | $ | 8,132 |  |  | $ | 6,391 |  |  | $ | 1,478 |  |  | $ | 1,430 |
Dominion Energy Questar Combination |  |  | — |  |  |  | 817 |  |  |  | — |  |  |  | 85 |
Service cost |  |  | 138 |  |  |  | 118 |  |  |  | 26 |  |  |  | 31 |
Interest cost |  |  | 345 |  |  |  | 317 |  |  |  | 60 |  |  |  | 65 |
Benefits paid |  |  | (323 | ) |  |  | (286 | ) |  |  | (83 | ) |  |  | (83 | )
Actuarial (gains) losses during the year |  |  | 830 |  |  |  | 784 |  |  |  | 119 |  |  |  | 166 |
Plan amendments(1) |  |  | 5 |  |  |  | — |  |  |  | (73 | ) |  |  | (216 | )
Settlements and curtailments(2) |  |  | (75 | ) |  |  | (9 | ) |  |  | 2 |  |  |  | — |
Benefit obligation at end of year |  | $ | 9,052 |  |  | $ | 8,132 |  |  | $ | 1,529 |  |  | $ | 1,478 |
Changes in fair value of plan assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at beginning of year |  | $ | 7,016 |  |  | $ | 6,166 |  |  | $ | 1,512 |  |  | $ | 1,382 |
Dominion Energy Questar Combination |  |  | — |  |  |  | 704 |  |  |  | — |  |  |  | 45 |
Actual return (loss) on plan assets |  |  | 1,327 |  |  |  | 426 |  |  |  | 236 |  |  |  | 108 |
Employer contributions |  |  | 118 |  |  |  | 15 |  |  |  | 13 |  |  |  | 12 |
Benefits paid |  |  | (323 | ) |  |  | (286 | ) |  |  | (32 | ) |  |  | (35 | )
Settlements(2) |  |  | (76 | ) |  |  | (9 | ) |  |  | — |  |  |  | — |
Fair value of plan assets at end of year |  | $ | 8,062 |  |  | $ | 7,016 |  |  | $ | 1,729 |  |  | $ | 1,512 |
Funded status at end of year |  | $ | (990 | ) |  | $ | (1,116 | ) |  | $ | 200 |  |  | $ | 34 |
Amounts recognized in the Consolidated Balance Sheets at December 31: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Noncurrent pension and other postretirement benefit assets |  | $ | 1,117 |  |  | $ | 930 |  |  | $ | 261 |  |  | $ | 148 |
Other current liabilities |  |  | (8 | ) |  |  | (43 | ) |  |  | — |  |  |  | (5 | )
Noncurrent pension and other postretirement benefit liabilities |  |  | (2,099 | ) |  |  | (2,003 | ) |  |  | (61 | ) |  |  | (109 | )
Net amount recognized |  | $ | (990 | ) |  | $ | (1,116 | ) |  | $ | 200 |  |  | $ | 34 |
Significant assumptions used to determine benefit obligations as of December 31: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate |  |  | 3.80%–3.81 | % |  |  | 3.31%–4.50 | % |  |  | 3.76% |  |  |  | 3.92%–4.47 | %
Weighted average rate of increase for compensation |  |  | 4.09 | % |  |  | 4.09 | % |  |  | 3.95%-4.11% |  |  |  | 3.29 | %
Dominion Energy Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Changes in benefit obligation: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligation at beginning of year |  | $ | 683 |  |  | $ | 608 |  |  | $ | 320 |  |  | $ | 292 |
Service cost |  |  | 15 |  |  |  | 13 |  |  |  | 4 |  |  |  | 5 |
Interest cost |  |  | 30 |  |  |  | 30 |  |  |  | 12 |  |  |  | 14 |
Benefits paid |  |  | (33 | ) |  |  | (32 | ) |  |  | (19 | ) |  |  | (19 | )
Actuarial (gains) losses during the year |  |  | 78 |  |  |  | 64 |  |  |  | 34 |  |  |  | 28 |
Plan amendments(1) |  |  | — |  |  |  | — |  |  |  | (61 | ) |  |  | — |
Benefit obligation at end of year |  | $ | 773 |  |  | $ | 683 |  |  | $ | 290 |  |  | $ | 320 |
Changes in fair value of plan assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at beginning of year |  | $ | 1,542 |  |  | $ | 1,467 |  |  | $ | 299 |  |  | $ | 283 |
Actual return (loss) on plan assets |  |  | 294 |  |  |  | 107 |  |  |  | 41 |  |  |  | 23 |
Employer contributions |  |  | — |  |  |  | — |  |  |  | 12 |  |  |  | 12 |
Benefits paid |  |  | (33 | ) |  |  | (32 | ) |  |  | (19 | ) |  |  | (19 | )
Fair value of plan assets at end of year |  | $ | 1,803 |  |  | $ | 1,542 |  |  | $ | 333 |  |  | $ | 299 |
Funded status at end of year |  | $ | 1,030 |  |  | $ | 859 |  |  | $ | 43 |  |  | $ | (21 | )
Amounts recognized in the Consolidated Balance Sheets at December 31: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Noncurrent pension and other postretirement benefit assets |  | $ | 1,030 |  |  | $ | 859 |  |  | $ | 57 |  |  | $ | — |
Noncurrent pension and other postretirement benefit liabilities(3) |  |  | — |  |  |  | — |  |  |  | (14 | ) |  |  | (21 | )
Net amount recognized |  | $ | 1,030 |  |  | $ | 859 |  |  | $ | 43 |  |  | $ | (21 | )
Significant assumptions used to determine benefit obligations as of December 31: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate |  |  | 3.81 | % |  |  | 4.50 | % |  |  | 3.76 | % |  |  | 4.47 | %
Weighted average rate of increase for compensation |  |  | 4.11 | % |  |  | 4.11 | % |  |  | n/a |  |  |  | n/a |
(1) | 2017 amounts relate primarily to a plan amendment that changed post-65 retiree medical coverage for certain current and future Local 69 retirees effective July 1, 2017. 2016 amount relates primarily to a plan amendment that changed post-65 retiree medical coverage for certain current and future Local 50 retirees effective April 1, 2017.
(2) | 2017 amount relates primarily to settlement and curtailment as a result of the voluntary and involuntary separation programs at Dominion Energy Questar. 2016 amount relates primarily to a settlement for certain executives.
(3) | Reflected in other deferred credits and other liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.
Benefit obligation in excess of plan asset | The following table provides information on the benefit obligations and fair value of plan assets for plans with a benefit obligation in excess of plan assets for Dominion Energy and Dominion Energy Gas (for employees represented by collective bargaining units):
|  | Pension Benefits |  |  | Other Postretirement Benefits |
As of December 31, |  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
(millions) |  |  |  |  |  |  |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligation |  | $ | 8,209 |  |  | $ | 7,386 |  |  |  | $191 |  |  |  | $470 |
Fair value of plan assets |  |  | 6,103 |  |  |  | 5,340 |  |  |  | 156 |  |  |  | 356 |
Dominion Energy Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligation |  | $ | — |  |  | $ | — |  |  |  | $157 |  |  |  | $320 |
Fair value of plan assets |  |  | — |  |  |  | — |  |  |  | 143 |  |  |  | 299 |
Accumulated benefit obligation in excess of plan assets | The following table provides information on the ABO and fair value of plan assets for Dominion Energy’s pension plans with an ABO in excess of plan assets:
As of December 31, |  | 2017 |  |  | 2016 |
(millions) |  |  |  |  |  |
Accumulated benefit obligation |  | $ | 7,392 |  |  | $ | 5,987 |
Fair value of plan assets |  |  | 6,103 |  |  |  | 4,653 |
Benefit payments expected future service | The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid for Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) plans:
|  | Estimated Future Benefit Payments |
|  | Pension Benefits |  |  | Other Postretirement Benefits |
(millions) |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |
2018 |  |  | $373 |  |  |  | $ 99 |
2019 |  |  | 378 |  |  |  | 101 |
2020 |  |  | 402 |  |  |  | 102 |
2021 |  |  | 418 |  |  |  | 102 |
2022 |  |  | 434 |  |  |  | 102 |
2023-2027 |  | 2,437 |  |  | 486 |
Dominion Energy Gas |  |  |  |  |  |  |  |
2018 |  |  | $ 35 |  |  |  | $ 19 |
2019 |  |  | 37 |  |  |  | 19 |
2020 |  |  | 38 |  |  |  | 20 |
2021 |  |  | 39 |  |  |  | 20 |
2022 |  |  | 41 |  |  |  | 20 |
2023-2027 |  |  | 214 |  |  |  | 94 |
Fair values of pension and post retirement plan assets by asset category | The fair values of Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) other postretirement plan assets by asset category are as follows:
At December 31, |  | 2017 |  |  | 2016 |
|  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |  |  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |
(millions) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  | $ 1 |  |  |  | $ 2 |  |  |  | $— |  |  | $ | 3 |  |  |  | $ 1 |  |  |  | $ 1 |  |  |  | $— |  |  |  | $ 2 |
Common and preferred stocks: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. |  |  | 636 |  |  |  | — |  |  |  | — |  |  |  | 636 |  |  |  | 571 |  |  |  | — |  |  |  | — |  |  |  | 571 |
International |  |  | 196 |  |  |  | — |  |  |  | — |  |  |  | 196 |  |  |  | 143 |  |  |  | — |  |  |  | — |  |  |  | 143 |
Insurance contracts |  |  | — |  |  |  | 21 |  |  |  | — |  |  |  | 21 |  |  |  | — |  |  |  | 19 |  |  |  | — |  |  |  | 19 |
Corporate debt instruments |  |  | 2 |  |  |  | 44 |  |  |  | — |  |  |  | 46 |  |  |  | 2 |  |  |  | 40 |  |  |  | — |  |  |  | 42 |
Government securities |  |  | 1 |  |  |  | 41 |  |  |  | — |  |  |  | 42 |  |  |  | 1 |  |  |  | 30 |  |  |  | — |  |  |  | 31 |
Total recorded at fair value |  |  | $836 |  |  |  | $108 |  |  |  | $— |  |  | $ | 944 |  |  |  | $718 |  |  |  | $90 |  |  |  | $— |  |  |  | $ 808 |
Assets recorded at NAV(1): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common/collective trust funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 689 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 621 |
Alternative investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9 |
Private equity funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 73 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 59 |
Debt funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 |
Hedge funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |
Total recorded at NAV |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 783 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 702 |
Total investments(2) |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 1,727 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $1,510 |
Dominion Energy Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common and preferred stocks: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. |  |  | $130 |  |  |  | $ — |  |  |  | $— |  |  | $ | 130 |  |  |  | $121 |  |  |  | $— |  |  |  | $— |  |  |  | $ 121 |
International |  |  | 33 |  |  |  | — |  |  |  | — |  |  |  | 33 |  |  |  | 24 |  |  |  | — |  |  |  | — |  |  |  | 24 |
Total recorded at fair value |  |  | $163 |  |  |  | $ — |  |  |  | $— |  |  | $ | 163 |  |  |  | $145 |  |  |  | $— |  |  |  | $— |  |  |  | $ 145 |
Assets recorded at NAV(1): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common/collective trust funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 154 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 140 |
Alternative investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |
Private equity funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 |
Debt funds |  |  |  |  |  |  |  |  |  |  |  |  |  |  | — |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |
Total recorded at NAV |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 170 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 154 |
Total investments |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 333 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 299 |
(1) | These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient which are not required to be categorized in the fair value hierarchy.
(2) | Excludes net assets related to pending sales of securities of $1 million, net accrued income of $2 million, and includes net assets related to pending purchases of securities of $1 million at December 31, 2017. Excludes net assets related to pending sales of securities of $5 million, net accrued income of $2 million, and includes net assets related to pending purchases of securities of $5 million at December 31, 2016.
Net periodic benefit (credit) cost and amounts recognized in other comprehensive income and regulatory assets and liabilities | The components of the provision for net periodic benefit (credit) cost and amounts recognized in other comprehensive income and regulatory assets and liabilities for Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) plans are as follows:
|  | Pension Benefits |  |  | Other Postretirement Benefits |
Year Ended December 31, |  | 2017 |  |  | 2016 |  |  | 2015 |  |  | 2017 |  |  | 2016 |  |  | 2015 |
(millions, except percentages) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 138 |  |  | $ | 118 |  |  | $ | 126 |  |  | $ | 26 |  |  | $ | 31 |  |  | $ | 40 |
Interest cost |  |  | 345 |  |  |  | 317 |  |  |  | 287 |  |  |  | 60 |  |  |  | 65 |  |  |  | 67 |
Expected return on plan assets |  |  | (639 | ) |  |  | (573 | ) |  |  | (531 | ) |  |  | (128 | ) |  |  | (118 | ) |  |  | (117 | )
Amortization of prior service (credit) cost |  |  | 1 |  |  |  | 1 |  |  |  | 2 |  |  |  | (51 | ) |  |  | (35 | ) |  |  | (27 | )
Amortization of net actuarial loss |  |  | 162 |  |  |  | 111 |  |  |  | 160 |  |  |  | 13 |  |  |  | 8 |  |  |  | 6 |
Settlements and curtailments |  |  | — |  |  |  | 1 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Net periodic benefit (credit) cost |  | $ | 7 |  |  | $ | (25 | ) |  | $ | 44 |  |  | $ | (80 | ) |  | $ | (49 | ) |  | $ | (31 | )
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current year net actuarial (gain) loss |  | $ | 142 |  |  | $ | 931 |  |  | $ | 159 |  |  | $ | 12 |  |  | $ | 178 |  |  | $ | (18 | )
Prior service (credit) cost |  |  | 5 |  |  |  | — |  |  |  | — |  |  |  | (73 | ) |  |  | (216 | ) |  |  | (31 | )
Settlements and curtailments |  |  | 1 |  |  |  | (1 | ) |  |  | — |  |  |  | 2 |  |  |  | — |  |  |  | — |
Less amounts included in net periodic benefit cost: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization of net actuarial loss |  |  | (162 | ) |  |  | (111 | ) |  |  | (160 | ) |  |  | (13 | ) |  |  | (8 | ) |  |  | (6 | )
Amortization of prior service credit (cost) |  |  | (1 | ) |  |  | (1 | ) |  |  | (2 | ) |  |  | 51 |  |  |  | 35 |  |  |  | 27 |
Total recognized in other comprehensive income and regulatory assets and liabilities |  | $ | (15 | ) |  | $ | 818 |  |  | $ | (3 | ) |  | $ | (21 | ) |  | $ | (11 | ) |  | $ | (28 | )
Significant assumptions used to determine periodic cost: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate |  |  | 3.31%-4.50 | % |  |  | 2.87%-4.99 | % |  |  | 4.40 | % |  |  | 3.92%-4.47 | % |  |  | 3.56%-4.94 | % |  |  | 4.40 | %
Expected long-term rate of return on plan assets |  |  | 8.75 | % |  |  | 8.75 | % |  |  | 8.75 | % |  |  | 8.50 | % |  |  | 8.50 | % |  |  | 8.50 | %
Weighted average rate of increase for compensation |  |  | 4.09 | % |  |  | 4.22 | % |  |  | 4.22 | % |  |  | 3.29 | % |  |  | 4.22 | % |  |  | 4.22 | %
Healthcare cost trend rate(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.00 | % |  |  | 7.00 | % |  |  | 7.00 | %
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00 | % |  |  | 5.00 | % |  |  | 5.00 | %
Year that the rate reaches the ultimate trend rate(1)(2) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2021 |  |  |  | 2020 |  |  |  | 2019 |
Dominion Energy Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 15 |  |  | $ | 13 |  |  | $ | 15 |  |  | $ | 4 |  |  | $ | 5 |  |  | $ | 7 |
Interest cost |  |  | 30 |  |  |  | 30 |  |  |  | 27 |  |  |  | 12 |  |  |  | 14 |  |  |  | 14 |
Expected return on plan assets |  |  | (141 | ) |  |  | (134 | ) |  |  | (126 | ) |  |  | (24 | ) |  |  | (23 | ) |  |  | (24 | )
Amortization of prior service (credit) cost |  |  | — |  |  |  | — |  |  |  | 1 |  |  |  | (3 | ) |  |  | 1 |  |  |  | (1 | )
Amortization of net actuarial loss |  |  | 16 |  |  |  | 13 |  |  |  | 20 |  |  |  | 2 |  |  |  | 1 |  |  |  | 2 |
Net periodic benefit (credit) cost |  | $ | (80 | ) |  | $ | (78 | ) |  | $ | (63 | ) |  | $ | (9 | ) |  | $ | (2 | ) |  | $ | (2 | )
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current year net actuarial (gain) loss |  | $ | (75 | ) |  | $ | 91 |  |  | $ | 97 |  |  | $ | 18 |  |  | $ | 28 |  |  | $ | (9 | )
Prior service cost |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (61 | ) |  |  | — |  |  |  | — |
Less amounts included in net periodic benefit cost: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization of net actuarial loss |  |  | (16 | ) |  |  | (13 | ) |  |  | (20 | ) |  |  | (2 | ) |  |  | (1 | ) |  |  | (2 | )
Amortization of prior service credit (cost) |  |  | — |  |  |  | — |  |  |  | (1 | ) |  |  | 3 |  |  |  | (1 | ) |  |  | 1 |
Total recognized in other comprehensive income and regulatory assets and liabilities |  | $ | (91 | ) |  | $ | 78 |  |  | $ | 76 |  |  | $ | (42 | ) |  | $ | 26 |  |  | $ | (10 | )
Significant assumptions used to determine periodic cost: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate |  |  | 4.50 | % |  |  | 4.99 | % |  |  | 4.40 | % |  |  | 4.47 | % |  |  | 4.93 | % |  |  | 4.40 | %
Expected long-term rate of return on plan assets |  |  | 8.75 | % |  |  | 8.75 | % |  |  | 8.75 | % |  |  | 8.50 | % |  |  | 8.50 | % |  |  | 8.50 | %
Weighted average rate of increase for compensation |  |  | 4.11 | % |  |  | 3.93 | % |  |  | 3.93 | % |  |  | 4.11 | % |  |  | 3.93 | % |  |  | 3.93 | %
Healthcare cost trend rate(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.00 | % |  |  | 7.00 | % |  |  | 7.00 | %
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00 | % |  |  | 5.00 | % |  |  | 5.00 | %
Year that the rate reaches the ultimate trend rate(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2021 |  |  |  | 2020 |  |  |  | 2019 |
(1) | Assumptions used to determine net periodic cost for the following year.
(2) | The Society of Actuaries model used to determine healthcare cost trend rates was updated in 2014. The new model converges to the ultimate trend rate much more quickly than previous models.
Components of AOCI and regulatory assets and liabilities that have not been recognized as components of periodic benefit (credit) cost | The components of AOCI and regulatory assets and liabilities for Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) plans that have not been recognized as components of net periodic benefit (credit) cost are as follows:
|  | Pension Benefits |  |  | Other Postretirement Benefits |
At December 31, |  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
(millions) |  |  |  |  |  |  |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net actuarial loss |  | $ | 3,181 |  |  | $ | 3,200 |  |  | $ | 283 |  |  | $ | 283 |
Prior service (credit) cost |  |  | 8 |  |  |  | 4 |  |  |  | (440 | ) |  |  | (419 | )
Total(1) |  | $ | 3,189 |  |  | $ | 3,204 |  |  | $ | (157 | ) |  | $ | (136 | )
Dominion Energy Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net actuarial loss |  | $ | 367 |  |  | $ | 458 |  |  | $ | 76 |  |  | $ | 60 |
Prior service (credit) cost |  |  | — |  |  |  | — |  |  |  | (52 | ) |  |  | 7 |
Total(2) |  | $ | 367 |  |  | $ | 458 |  |  | $ | 24 |  |  | $ | 67 |
(1) | As of December 31, 2017, of the $3.2 billion and $(157) million related to pension benefits and other postretirement benefits, $1.9 billion and $(87) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities. As of December 31, 2016, of the $3.2 billion and $(136) million related to pension benefits and other postretirement benefits, $1.9 billion and $(103) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities.
(2) | As of December 31, 2017, of the $367 million related to pension benefits, $134 million is included in AOCI, with the remainder included in regulatory assets and liabilities; the $24 million related to other postretirement benefits is included entirely in regulatory assets and liabilities. As of December 31, 2016, of the $458 million related to pension benefits, $167 million is included in AOCI, with the remainder included in regulatory assets and liabilities; the $67 million related to other postretirement benefits is included entirely in regulatory assets and liabilities.
Components of AOCI and regulatory assets and liabilities that are expected to be amortized as components of periodic benefit cost in 2017 | The following table provides the components of AOCI and regulatory assets and liabilities for Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) plans as of December 31, 2017 that are expected to be amortized as components of net periodic benefit (credit) cost in 2018:
|  | Pension Benefits |  |  | Other Postretirement Benefits |
(millions) |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |
Net actuarial loss |  |  | $193 |  |  |  | $ 11 |
Prior service (credit) cost |  |  | 1 |  |  |  | (52 | )
Dominion Energy Gas |  |  |  |  |  |  |  |
Net actuarial loss |  |  | $ 19 |  |  |  | $ 3 |
Prior service (credit) cost |  |  | — |  |  |  | (4 | )
Effect of one percentage point change on benefit plans | A one percentage point change in assumed healthcare cost trend rates would have had the following effects for Dominion Energy’s and Dominion Energy Gas’ (for employees represented by collective bargaining units) other postretirement benefit plans:
|  | Other Postretirement Benefits |
|  | One percentage point increase |  |  | One percentage point decrease |
(millions) |  |  |  |  |  |
Dominion Energy |  |  |  |  |  |  |  |
Effect on net periodic cost for 2018 |  |  | $ 24 |  |  |  | $ (15 | )
Effect on other postretirement benefit obligation at December 31, 2017 |  |  | 158 |  |  |  | (132 | )
Dominion Energy Gas |  |  |  |  |  |  |  |
Effect on net periodic cost for 2018 |  |  | $ 4 |  |  |  | $ (3 | )
Effect on other postretirement benefit obligation at December 31, 2017 |  |  | 31 |  |  |  | (26 | )

X
- Definition Components Of AOCI And Regulatory Assets And Liabilities that Are Expected To Be Amortized As Components Of Periodic Benefit Cost [Text Block] + References No definition available. + Details
Name: | d_ComponentsOfAOCIAndRegulatoryAssetsAndLiabilitiesThatAreExpectedToBeAmortizedAsComponentsOfPeriodicBenefitCostTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Components Of AOCI And Regulatory Assets And Liabilities That Have Not Been Recognized As Components Of Periodic Benefit Credit Cost [Text Block] + References No definition available. + Details
Name: | d_ComponentsOfAociAndRegulatoryAssetsAndLiabilitiesThatHaveNotBeenRecognizedAsComponentsOfPeriodicBenefitCreditCostTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Net Periodic Benefit Credit Cost And Amounts Recognized In Other Comprehensive Income And Regulatory Assets And Liabilities Text Block + References No definition available. + Details
Name: | d_NetPeriodicBenefitCreditCostAndAmountsRecognizedInOtherComprehensiveIncomeAndRegulatoryAssetsAndLiabilitiesTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Accumulated Benefit Obligation In Excess Of Plan Assets Text Block + References No definition available. + Details
Name: | d_ScheduleOfAccumulatedBenefitObligationInExcessOfPlanAssetsTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Benefit Obligation In Excess Of Plan Assets Disclosure Text Block + References No definition available. + Details
Name: | d_ScheduleOfBenefitObligationInExcessOfPlanAssetsDisclosureTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Benefit Payments Expected Future Service Text Block + References No definition available. + Details
Name: | d_ScheduleOfBenefitPaymentsExpectedFutureServiceTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Effect Of One Percentage Point Change On Benefit Plans Text Block + References No definition available. + Details
Name: | d_ScheduleOfEffectOfOnePercentagePointChangeOnBenefitPlansTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Fair Values Of Pension Plan And Postretirement Plan Assets By Asset Category Text Block + References No definition available. + Details
Name: | d_ScheduleOfFairValuesOfPensionPlanAndPostretirementPlanAssetsByAssetCategoryTextBlockTableTextBlock
Namespace Prefix: | d_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the change in the benefit obligation, fair value of plan assets, and funded status of pension plans or other employee benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(b)(c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_ChangesInProjectedBenefitObligationsFairValueOfPlanAssetsAndFundedStatusOfPlanTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration