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Non-controlling Interest - Changes in Non-controlling Interest (Detail) - USD ($) $ in Millions | 6 Months Ended
--- | ---
Jun. 30, 2018 | Jun. 30, 2017
Noncontrolling Interest [Line Items] |  |
Beginning balance | $ 399 |
Net income attributable to non-controlling interest in 2018 | (160) | $ (23)
Ending balance | 64 |
Ship Finance International Ltd VIEs [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | (59) |
Net income attributable to non-controlling interest in 2018 | 7 |
Ending balance | (52) |
North Atlantic Drilling Ltd [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | 76 |
Net income attributable to non-controlling interest in 2018 | (160) |
Ending balance | (109) |
Asia Offshore Drilling [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | 149 |
Net income attributable to non-controlling interest in 2018 | 1 |
Redeemable non-controlling interest | (150) |
Sevan Drilling Asa [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | 226 |
Net income attributable to non-controlling interest in 2018 | (10) |
Ending balance | 216 |
Seadrill Nigeria Operations Limited [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | 7 |
Net income attributable to non-controlling interest in 2018 | 2 |
Ending balance | 9 |
Accounting standards update 2016-16 |  |
Noncontrolling Interest [Line Items] |  |
Adoption of new accounting standard ASU 2016-16 - Income Taxes | (84) |
Accounting standards update 2016-16 | North Atlantic Drilling Ltd [Member] |  |
Noncontrolling Interest [Line Items] |  |
Adoption of new accounting standard ASU 2016-16 - Income Taxes | (25) |
Non-controlling Interest [Member] |  |
Noncontrolling Interest [Line Items] |  |
Beginning balance | 399 |
Net income attributable to non-controlling interest in 2018 | (160) |
Redeemable non-controlling interest | (150) |
Ending balance | 64 |
Non-controlling Interest [Member] | Accounting standards update 2016-16 |  |
Noncontrolling Interest [Line Items] |  |
Adoption of new accounting standard ASU 2016-16 - Income Taxes | $ (25) |

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- Definition Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(22)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(24)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.31) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of Net Income (Loss) attributable to noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4J -URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4591551-111686 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=84161450&loc=SL4573702-111684 + Details
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