Revisions of Previously Issued Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (Decrease) in Other Operating Assets and Liabilities, Net	$ (9)	$ (97)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations	155	54
Increase (Decrease) in Client Funds Held	0	(12)
Net Cash Provided by (Used in) Investing Activities	(218)	(98)
Net Cash Provided by (Used in) Financing Activities	98	765
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(15)	710
Cash, Cash Equivalents, Restricted Cash at end of period	$ 391	1,273
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (Decrease) in Other Operating Assets and Liabilities, Net		(90)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		61
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		717
Cash, cash equivalents and restricted cash at beginning of period		548
Cash, Cash Equivalents, Restricted Cash at end of period		1,265
Revision of Prior Period, Error Correction, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (Decrease) in Other Operating Assets and Liabilities, Net		(7)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		(7)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		(7)
Cash, cash equivalents and restricted cash at beginning of period		15
Cash, Cash Equivalents, Restricted Cash at end of period		8
As Revised
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (Decrease) in Other Operating Assets and Liabilities, Net		(97)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		54
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		710
Cash, cash equivalents and restricted cash at beginning of period		563
Cash, Cash Equivalents, Restricted Cash at end of period		$ 1,273

Cash, cash equivalents and restricted cash at beginning of period

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Cash, Cash Equivalents, Restricted Cash at end of period

+ References

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Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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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.

+ References

No definition available.

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The increase (decrease) during the reporting period in the carrying amount of client funds held and maintained in custodial and separate accounts, and which are owned by clients or contract holders.

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Amount of increase (decrease) in operating assets after deduction of operating liabilities classified as other.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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