Other Assets - Equity Method Investments and Leases - Investees (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Mitsubishi UFJ Morgan Stanley Securities Co., Ltd
Equity Method Investments
Income from investment in MUMSS	$ 168	$ 80	$ 17

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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