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Debt (Narrative) (Details) £ in Billions |  | 1 Months Ended | 3 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 18, 2018 USD ($) | Mar. 31, 2020 USD ($) | Jan. 31, 2020 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Apr. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Oct. 31, 2018 | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Apr. 30, 2020 USD ($) | Dec. 31, 2019 USD ($) | Apr. 01, 2019 USD ($) | Mar. 31, 2019 EUR (€) | Jan. 31, 2019 USD ($) | Oct. 01, 2018 USD ($) | Sep. 30, 2018 USD ($) | Sep. 18, 2018 GBP (£)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commercial paper outstanding |  | $ 193,000,000 |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  |  |
$300 Million One-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  |  |  |  |  | $ 300,000,000 |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |
$300 Million Three-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term line of credit |  |  |  |  |  |  | $ 300,000,000 |  |  | 300,000,000 |  |  |  |  |  |  |  |  |
1.349% Senior Debt Obligations Due 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  | 1.349% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
1.979% Senior Debt Obligations Due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  | 1.979% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commercial Paper |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Short-term debt |  | $ 1,500,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Effective interest rate |  | 3.04% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Jardine Lloyd Thompson Group plc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt |  |  |  |  | $ 553,000,000 | $ 450,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Debt assumed in acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000,000 |  |  |  |  |
Payments for early extinguishment of debt |  |  |  |  |  |  |  |  | $ 32,000,000 |  |  |  |  |  |  |  |  |  |
Jardine Lloyd Thompson Group plc | Bridge Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative, notional amount | £ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | £ 5.2
Payments of debt issuance costs | $ 35,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization of debt issuance costs |  |  |  |  |  |  |  |  |  |  | $ 30,000,000 |  |  |  |  |  |  |  |
Interest expense, debt |  |  |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |
Term Loan Facility | $500 Million One-Year Term Loan and $500 Million Two-Year Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term line of credit |  | $ 1,000,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term Loan Facility | $500 Million One-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  | 1 year |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term Loan Facility | $500 Million Two-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term Loan Facility | $300 Million One-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |  |  |  |  |  |
Term Loan Facility | $300 Million Three-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |
Revolving Credit Facility | Amended Revolving Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,800,000,000 | $ 1,500,000,000 |
Term of debt |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |
Long-term line of credit |  | 1,000,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt |  | 500,000,000 |  | $ 300,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000,000,000 |  |  |
Senior Notes | 1.349% Senior Debt Obligations Due 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount | € |  |  |  |  |  |  |  |  |  |  |  |  |  |  | € 550,000,000 |  |  |  |
Interest rate |  |  |  |  |  |  | 1.349% |  |  | 1.349% |  |  |  |  | 1.349% |  |  |  |
Senior Notes | 1.979% Senior Debt Obligations Due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount | € |  |  |  |  |  |  |  |  |  |  |  |  |  |  | € 550,000,000 |  |  |  |
Interest rate |  |  |  |  |  |  | 1.979% |  |  | 1.979% |  |  |  |  | 1.979% |  |  |  |
Senior Notes | Senior Debt Obligations 4.375% Due 2029 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  | $ 1,500,000,000 |  |  |  |  | $ 250,000,000 |  |  | $ 250,000,000 |  |  |  |  |  | 1,250,000,000 |  |  |
Interest rate |  | 4.375% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes | Senior Debt Obligations 3.50% Due 2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 700,000,000 |  |  |
Interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.50% |  |  |
Senior Notes | Senior Debt Obligations 3.875% Due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000,000 |  |  |
Interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.875% |  |  |
Senior Notes | Senior Debt Obligations 4.75% Due 2039 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 500,000,000 |  |  |
Interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.75% |  |  |
Senior Notes | Senior Debt Obligations 4.90% Due 2049 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,250,000,000 |  |  |
Interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.90% |  |  |
Senior Notes | Floating Rate Senior Notes Due 2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000,000 |  |  |
Senior Notes | Jardine Lloyd Thompson Group plc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount | € |  |  |  |  |  |  |  |  |  |  |  |  |  |  | € 1,100,000,000 |  |  |  |
Subsequent Event | April 2020 New Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt facilities, maximum borrowing capacity |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000,000 |  |  |  |  |  |  |

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- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: 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(13)(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: 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(a)(16)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 3: 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(19)(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 3: 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Nominal or face amount used to calculate payments on the derivative asset. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959 + Details
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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=119400593&loc=d3e572229-122910 + Details
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