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Debt (Narrative) (Details) £ in Billions |  | 1 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Sep. 18, 2018 USD ($) | Apr. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) | Oct. 01, 2018 USD ($) | Sep. 18, 2018 GBP (£) | Dec. 31, 2017 USD ($) | Jan. 31, 2017 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |
Commercial paper outstanding |  |  | $ 75,000,000 |  |  | $ 0 |
Repayments of senior debt |  | $ 250,000,000 |  |  |  |  |
4.20% Senior Debt Obligations Due 2048 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Proceeds from issuance of debt |  |  | $ 600,000,000 |  |  |  |
Interest rate |  |  | 4.20% |  |  |  |
2.75% Senior Debt Obligations Due 2022 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Proceeds from issuance of debt |  |  |  |  |  |  | $ 500,000,000
Interest rate |  |  | 2.75% |  |  |  | 2.75%
4.35% Senior Debt Obligation Due 2047 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Proceeds from issuance of debt |  |  |  |  |  |  | $ 500,000,000
Interest rate |  |  | 4.35% |  |  |  | 4.35%
3.30% Senior Debt Obligations Due 2023 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Interest rate |  |  | 3.30% |  |  |  |
Amended Revolving Credit Facility March 27, 2014 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  | $ 1,500,000,000.0 |  |  |  |
Term of debt |  |  | 5 years |  |  |  |
Revolving credit facility, amount outstanding |  |  | $ 0 |  |  |  |
Commercial Paper |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Debt financing program |  |  | $ 1,500,000,000 |  |  |  |
Effective interest rate |  |  | 2.41% |  |  |  |
Bridge Loan |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Duration fee ninety days after first borrowing, percent |  |  | 50.00% |  |  |  |
Duration fee one hundred and eighty days after first borrowing, percent |  |  | 75.00% |  |  |  |
Duration fee two hundred and seventy days after first borrowing, percent |  |  | 100.00% |  |  |  |
Jardine Lloyd Thompson Group plc | Bridge Loan |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Derivative, notional amount | £ |  |  |  |  | £ 5.2 |  |
Payments of debt issuance costs | $ 24,000,000 |  |  |  |  |  |
Amortization of debt issuance costs | $ 3,000,000 |  |  |  |  |  |
Subsequent Event | Amended Revolving Credit Facility March 27, 2014 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  |  | $ 1,800,000,000 |  |  |

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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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