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Accounting Policies - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Jun. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019 | Jun. 30, 2019 | Dec. 31, 2018
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |
Cumulative effect of accounting change | $ 6,340 | $ 6,321 | $ 6,340 | $ 6,321 | $ 6,126 |  | $ 6,269 | $ 6,090 | $ 4,972
Assets of managed investment entities | 73,110 |  | 73,110 |  |  |  | 70,130 |  |
Liabilities of managed investment entities | 66,770 |  | 66,770 |  |  |  | 63,861 |  |
Operating lease liability | 175 |  | 175 |  |  |  | 180 |  |
Operating lease right-of-use asset | $ 154 |  | $ 154 |  |  |  | 158 |  |
Weighted average common shares adjustment related to stock-based compensation (shares) | 300,000 | 1,100,000 | 500,000 | 1,200,000 |  |  |  |  |
Anti-dilutive potential common shares related to stock-based compensation plans (shares) | 0 | 0 | 0 | 0 |  |  |  |  |
Maturities of short term investments |  |  | 3 months |  |  |  |  |  |
New collateralized loan obligation temporary warehousing entity |  |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |
Assets of managed investment entities | $ 140 |  | $ 140 |  |  |  |  |  |
Liabilities of managed investment entities | 130 |  | 130 |  |  |  |  |  |
Retained Earnings |  |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |
Cumulative effect of accounting change | $ 3,737 | $ 4,022 | $ 3,737 | $ 4,022 | $ 3,685 |  | $ 4,009 | $ 3,914 | $ 3,588
Cumulative effect adjustment in period of adoption | Retained Earnings | Accounting Standards Update 2016-13 |  |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  |  |  |  | $ 7 |  |  |

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