Related Parties - Summary of Assets Sub-Advised by Affiliates (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Mortgage loans	$ 9,371	$ 6,233
Investment funds	3,390	2,580
Total assets	118,204	99,747
Apollo affiliates \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Mortgage loans	3,202	2,232
Investment funds	28	26
Trading securities	103	121
Funds withheld at interest	2,720	1,737
Other investments	72	75
Total assets	$ 16,869	$ 13,996
Percent of assets sub-advised by Apollo affiliates to total AAM-managed assets	17.00%	18.00%
Apollo affiliates \| Foreign governments \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Available-for-sale securities	$ 173	$ 152
Apollo affiliates \| Corporate \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Available-for-sale securities	3,409	2,934
Apollo affiliates \| CLO \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Available-for-sale securities	5,636	5,166
Apollo affiliates \| ABS \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Available-for-sale securities	652	681
Apollo affiliates \| CMBS \| Related party \| Assets sub-advised
Related Party Transaction [Line Items]
Available-for-sale securities	$ 874	$ 872

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

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Related Party Transaction, Percentage of Assets Managed

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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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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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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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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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