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Employee Benefits - Amounts recognized in Accumulated other comprehensive loss that have not yet been recognized (Details) - Pension Plan - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
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U.S. |  |
Amounts recognized in Accumulated other comprehensive loss unrecognized as components of net periodic benefit cost |  |
Net loss | $ 1,762 | $ 1,705
Prior service cost (income) | 1 | 3
Net amount recognized | 1,763 | 1,708
U.K. |  |
Amounts recognized in Accumulated other comprehensive loss unrecognized as components of net periodic benefit cost |  |
Net loss | 1,204 | 1,106
Prior service cost (income) | 40 | 30
Net amount recognized | 1,244 | 1,136
Other |  |
Amounts recognized in Accumulated other comprehensive loss unrecognized as components of net periodic benefit cost |  |
Net loss | 460 | 440
Prior service cost (income) | (6) | (7)
Net amount recognized | $ 454 | $ 433

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- Definition Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 + Details
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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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