Consolidated Statements of Cash Flows (Parenthetical) £ in Millions |
1 Months Ended | 12 Months Ended | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2017
GBP (£)
|
Nov. 30, 2016
USD ($)
|
Dec. 31, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
|
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| Tax Benefit from Tax Cuts and Jobs Act of 2017 | [1],[2] | $ 596,000,000 | $ 10,660,000,000 | $ 0 | ||||||||||||||
| Tax benefits associated with the enactment of the TCJA | [3] | 596,000,000 | 10,660,000,000 | 0 | ||||||||||||||
| Loss on early retirement of debt | $ 999,000,000 | $ 312,000,000 | $ 3,000,000 | [4] | 999,000,000 | [4] | $ 312,000,000 | [4] | ||||||||||
| Senior Unsecured U.K. Pound Debt, 6.50%, Due 2038 [Member] | ||||||||||||||||||
| Loss on early retirement of debt | $ 846,000,000 | |||||||||||||||||
| U.K. Pound Denominated Debt [Member] | ||||||||||||||||||
| Loss on exchange of debt | 747,000,000 | |||||||||||||||||
| Senior Notes [Member] | Senior Unsecured U.K. Pound Debt, 6.50%, Due 2038 [Member] | ||||||||||||||||||
| Amount of debt exchanged | £ 833 | $ 1,100,000,000 | ||||||||||||||||
| Interest rate, percentage | 6.50% | 6.50% | ||||||||||||||||
| Senior Notes [Member] | Senior Unsecured U.K. Pound Debt, 2.735%, Due 2043 [Member] | ||||||||||||||||||
| Interest rate, percentage | 2.735% | 2.735% | ||||||||||||||||
| Debt instrument, face amount | $ 1,800,000,000 | $ 1,800,000,000 | ||||||||||||||||
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