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Employee Benefit Plans (Fair values of pension and post retirement plan assets by asset category) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Pension Benefits |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | $ 7,016 | $ 6,166 | $ 6,480
Pension Benefits | Dominion Gas Holdings, LLC |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1,542 | 1,467 | 1,510
Other Postretirement Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1,512 | 1,382 | 1,402
Other Postretirement Plans | Dominion Gas Holdings, LLC |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 299 | 283 | $ 288
Collective Bargaining Agreement | Pension Benefits |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 4,233 | 4,082 |
Total recorded at NAV | [1] | 2,765 | 2,074 |
Pension plan assets by asset category | [2] | 6,998 | 6,156 |
Pending sales of securities |  | 46 | 112 |
Net accrued income |  | 19 | 16 |
Pending purchases of securities |  | 47 | 118 |
Collective Bargaining Agreement | Pension Benefits | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 14 | 16 |
Collective Bargaining Agreement | Pension Benefits | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1,705 | 1,736 |
Collective Bargaining Agreement | Pension Benefits | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 928 | 786 |
Collective Bargaining Agreement | Pension Benefits | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 334 | 330 |
Collective Bargaining Agreement | Pension Benefits | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 717 | 739 |
Collective Bargaining Agreement | Pension Benefits | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 535 | 475 |
Collective Bargaining Agreement | Pension Benefits | Common/collective trust funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1],[3] | 1,960 | 1,200 |
Collective Bargaining Agreement | Pension Benefits | Common/collective trust funds | Northern Trust Collective Short Term Investment Fund |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV |  | 167 | 125 |
Collective Bargaining Agreement | Pension Benefits | Real estate funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1] | 121 | 153 |
Collective Bargaining Agreement | Pension Benefits | Private equity funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [3] | 506 | 465 |
Collective Bargaining Agreement | Pension Benefits | Debt funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [3] | 153 | 170 |
Collective Bargaining Agreement | Pension Benefits | Hedge funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1] | 25 | 86 |
Collective Bargaining Agreement | Pension Benefits | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 2,693 | 2,667 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 12 | 16 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1,705 | 1,736 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 928 | 786 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 35 | 44 |
Collective Bargaining Agreement | Pension Benefits | Level 1 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 13 | 85 |
Collective Bargaining Agreement | Pension Benefits | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1,540 | 1,415 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 2 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 334 | 330 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 682 | 695 |
Collective Bargaining Agreement | Pension Benefits | Level 2 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 522 | 390 |
Collective Bargaining Agreement | Pension Benefits | Level 3 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Level 3 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 930 | 970 |
Total recorded at NAV | [1] | 608 | 494 |
Pension plan assets by asset category | [4] | 1,538 | 1,464 |
Pending sales of securities |  | 10 | 27 |
Net accrued income |  | 4 |  |
Pending purchases of securities |  | 10 | 28 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 3 | 4 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 375 | 413 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 203 | 187 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 73 | 78 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 158 | 175 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 118 | 113 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Common/collective trust funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1],[5] | 430 | 286 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Common/collective trust funds | Northern Trust Collective Short Term Investment Fund |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV |  | 37 | 30 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Real estate funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1] | 27 | 36 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Private equity funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [3] | 111 | 111 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Debt funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [3] | 34 | 40 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Hedge funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [1] | 6 | 21 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 592 | 634 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 3 | 4 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 375 | 413 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 203 | 187 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 8 | 10 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 3 | 20 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 338 | 336 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 73 | 78 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 150 | 165 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 115 | 93 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 808 | 752 |
Total recorded at NAV | [6] | 702 | 630 |
Pension plan assets by asset category | [7] | 1,510 | 1,382 |
Pending sales of securities |  | 5 |  |
Net accrued income |  | 2 |  |
Pending purchases of securities |  | 5 |  |
Collective Bargaining Agreement | Other Postretirement Plans | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 2 | 2 |
Collective Bargaining Agreement | Other Postretirement Plans | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 571 | 531 |
Collective Bargaining Agreement | Other Postretirement Plans | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 143 | 134 |
Collective Bargaining Agreement | Other Postretirement Plans | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 19 | 18 |
Collective Bargaining Agreement | Other Postretirement Plans | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 42 | 41 |
Collective Bargaining Agreement | Other Postretirement Plans | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 31 | 26 |
Collective Bargaining Agreement | Other Postretirement Plans | Common/collective trust funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [6],[8] | 621 | 543 |
Collective Bargaining Agreement | Other Postretirement Plans | Common/collective trust funds | Northern Trust Collective Short Term Investment Fund |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV |  | 16 | 9 |
Collective Bargaining Agreement | Other Postretirement Plans | Real estate funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [6] | 9 | 14 |
Collective Bargaining Agreement | Other Postretirement Plans | Private equity funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [6] | 59 | 54 |
Collective Bargaining Agreement | Other Postretirement Plans | Debt funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [6] | 12 | 14 |
Collective Bargaining Agreement | Other Postretirement Plans | Hedge funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [6] | 1 | 5 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 718 | 673 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1 | 1 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 571 | 531 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 143 | 134 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 2 | 3 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1 | 4 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 90 | 79 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 1 | 1 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 |  |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 |  |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 19 | 18 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 40 | 38 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 30 | 22 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Cash equivalents and other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 |  |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 |  |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Insurance contracts |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Corporate debt instruments |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Government securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 145 | 137 |
Total recorded at NAV | [9] | 154 | 146 |
Pension plan assets by asset category |  | 299 | 283 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 121 | 113 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 24 | 24 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Common/collective trust funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [7],[9] | 140 | 132 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Common/collective trust funds | Northern Trust Collective Short Term Investment Fund |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV |  | 2 | 3 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Real estate funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [9] | 1 | 2 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Private equity funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [9] | 12 | 11 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Debt funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at NAV | [9] | 1 | 1 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 145 | 137 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 121 | 113 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 24 | 24 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | Common and preferred stocks | U.S. |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | 0 | 0 |
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | Common and preferred stocks | International |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total recorded at fair value |  | $ 0 | $ 0 |
[1] | These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.
[2] | Includes net assets related to pending sales of securities of $46 million, net accrued income of $19 million, and excludes net assets related to pending purchases of securities of $47 million at December 31, 2016. Includes net assets related to pending sales of securities of $112 million, net accrued income of $16 million, and excludes net assets related to pending purchases of securities of $118 million at December 31, 2015.
[3] | Also included in the common collective trust funds is the Northern Trust Collective Short-Term Investment Fund, totaling $167 million and $125 million at December 31, 2016 and 2015, respectively, which is comprised of money market instruments with short-term maturities used for temporary investment. Liquidity is emphasized to provide for redemption of units on any business day. Principal preservation is also a prime objective. Admissions and withdrawals are made daily. Interest is accrued daily and distributed monthly.
[4] | Includes net assets related to pending sales of securities of $10 million, net accrued income of $4 million, and excludes net assets related to pending purchases of securities of $10 million at December 31, 2016. Includes net assets related to pending sales of securities of $27 million, net accrued income of $4 million, and excludes net assets related to pending purchases of securities of $28 million at December 31, 2015.
[5] | Also included in the common collective trust funds is the Northern Trust Collective Short-Term Investment Fund, totaling $37 million and $30 million at December 31, 2016 and 2015, respectively, which is comprised of money market instruments with short-term maturities used for temporary investment. Liquidity is emphasized to provide for redemption of units on any business day. Principal preservation is also a prime objective. Admissions and withdrawals are made daily. Interest is accrued daily and distributed monthly.
[6] | Also included in the common collective trust funds is the Northern Trust Collective Short-Term Investment Fund, totaling $16 million and $9 million at December 31, 2016 and 2015, respectively, which is comprised of money market instruments with short-term maturities used for temporary investment. Liquidity is emphasized to provide for redemption of units on any business day. Principal preservation is also a prime objective. Admissions and withdrawals are made daily. Interest is accrued daily and distributed monthly.
[7] | Includes net assets related to pending sales of securities of $5 million, net accrued income of $2 million, and excludes net assets related to pending purchases of securities of $5 million at December 31, 2016.
[8] | These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.
[9] | Also included in the common collective trust funds is the Northern Trust Collective Short-Term Investment Fund, totaling $2 million and $3 million at December 31, 2016 and 2015, respectively, which is comprised of money market instruments with short-term maturities used for temporary investment. Liquidity is emphasized to provide for redemption of units on any business day. Principal preservation is also a prime objective. Admissions and withdrawals are made daily. Interest is accrued daily and distributed monthly.

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