Fair Value - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets
Mortgage loans	$ 10,631	$ 6,233
Investment funds	3,559	2,580
Consolidated Entity Excluding Variable Interest Entities (VIE)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	991	0
Liabilities
Interest sensitive contract liabilities	96,610	68,099
Funds withheld liability	721	407
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	991
Assets
Mortgage loans	10,308	6,192
Investment funds	521	554
Policy loans	488	542
Funds withheld at interest	14,966	6,773
Other investments	70	133
Total assets not carried at fair value	42,805	15,734
Liabilities
Interest sensitive contract liabilities	54,655	31,878
Funds withheld liability	722	385
Total liabilities not carried at fair value	56,368	32,263
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	910
Assets
Mortgage loans	10,424	6,342
Investment funds	521	554
Policy loans	488	542
Funds withheld at interest	14,966	6,773
Other investments	70	133
Total assets not carried at fair value	42,895	15,905
Liabilities
Interest sensitive contract liabilities	51,655	31,656
Funds withheld liability	722	385
Total liabilities not carried at fair value	53,287	32,041
Consolidated Entity Excluding Variable Interest Entities (VIE) \| NAV \| Fair Value
Assets
Investment funds	521	554
Total assets not carried at fair value	2,609	1,856
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Level 1 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	0
Assets
Mortgage loans	0	0
Investment funds	0	0
Policy loans	0	0
Funds withheld at interest	0	0
Other investments	0	0
Total assets not carried at fair value	0	0
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	0	0
Total liabilities not carried at fair value	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Level 2 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	910
Assets
Mortgage loans	0	0
Investment funds	0	0
Policy loans	488	542
Funds withheld at interest	0	0
Other investments	0	58
Total assets not carried at fair value	488	600
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	722	385
Total liabilities not carried at fair value	1,632	385
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Level 3 \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	0
Assets
Mortgage loans	10,424	6,342
Investment funds	0	0
Policy loans	0	0
Funds withheld at interest	14,966	6,773
Other investments	70	75
Total assets not carried at fair value	39,798	13,449
Liabilities
Interest sensitive contract liabilities	51,655	31,656
Funds withheld liability	0	0
Total liabilities not carried at fair value	51,655	31,656
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party
Assets
Mortgage loans	291	0
Investment funds	2,232	1,310
Funds withheld at interest	13,577	0
Other investments	386	238
Short-term investments	0	52
Liabilities
Interest sensitive contract liabilities	16,850	0
Funds withheld liability	337	0
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| Carrying Value
Assets
Mortgage loans	291
Investment funds	2,031	1,280
Funds withheld at interest	13,687
Other investments	386	238
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| Fair Value
Assets
Mortgage loans	290
Investment funds	2,031	1,280
Funds withheld at interest	13,687
Other investments	361	259
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| NAV \| Fair Value
Assets
Investment funds	2,031	1,280
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| Level 1 \| Fair Value
Assets
Mortgage loans	0
Investment funds	0	0
Funds withheld at interest	0
Other investments	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| Level 2 \| Fair Value
Assets
Mortgage loans	0
Investment funds	0	0
Funds withheld at interest	0
Other investments	0	0
Consolidated Entity Excluding Variable Interest Entities (VIE) \| Related Party \| Level 3 \| Fair Value
Assets
Mortgage loans	290
Investment funds	0	0
Funds withheld at interest	13,687
Other investments	361	259
Variable Interest Entities
Assets
Investment funds	624	571
Variable Interest Entities \| Related Party
Assets
Investment funds	583	571
Variable Interest Entities \| Related Party \| Carrying Value
Assets
Investment funds	57	22
Variable Interest Entities \| Related Party \| Fair Value
Assets
Investment funds	57	22
Variable Interest Entities \| Related Party \| NAV \| Fair Value
Assets
Investment funds	57	22
Variable Interest Entities \| Related Party \| Level 1 \| Fair Value
Assets
Investment funds	0	0
Variable Interest Entities \| Related Party \| Level 2 \| Fair Value
Assets
Investment funds	0	0
Variable Interest Entities \| Related Party \| Level 3 \| Fair Value
Assets
Investment funds	$ 0	$ 0

Other investments including, but not limited to: partnership interests, credit funds, hedge funds, and private equity.

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Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Amount of the reinsurer's funds held on its behalf by the ceding insurer, including funds held in trust, under reinsurance treaties or contracts with the assuming insurer as security for the payment of the obligations thereunder.

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Amount of funds held as security for payments to be received under reinsurance contracts.

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Amount before allowance of loans made to policy and contract holders using their life insurance contracts' cash value or separate accounts as collateral. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums over and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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Amount of investments classified as other.

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The liability as of the balance sheet date to the policyholders for deposits held under the terms of insurance contracts.

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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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