Condensed Consolidating Supplemental Guarantor Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2017
Proceeds from Contributions from Parent		$ 0
Net cash provided by (used in) operating activities	$ 61	(16)
Investing activities
Expenditures for property, plant and equipment	(10)	(22)
Proceeds from sale of property, plant and equipment	7	0
Additions to capitalized software	(69)	(43)
Proceeds from (payments of) intercompany notes	0	0
Investments in equity affiliates		0
Business acquisitions, net	(26)	(6)
Net change in funds held for clients - investing	0	0
Increase (Decrease) in Client Funds Held	12	17
Other investing activities, net	0	3
Net Cash Provided by (Used in) Investing Activities	(98)	(68)
Financing activities
Short term borrowings, net	(3)	(7)
Payments on term credit facilities	(2)	(17)
Payments on revolving credit facilities	(573)	(375)
Borrowings on revolving credit facilities	1,397	430
Repurchases of Common Stock	(41)	0
Payments of Debt Issuance Costs	(1)	0
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	(6)	0
Proceeds from employee stock plans	3	4
Proceeds from (Payments for) Other Financing Activities	(3)	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	0
Borrowings (repayments) of intercompany notes	0	0
Tax withholding payments on behalf of employees	(24)	(13)
Net Cash Provided by (Used in) Financing Activities	765	53
Cash flows from discontinued operations
Net cash provided by (used in) operating activities	3	(6)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(14)	1
Increase (decrease) in cash, cash equivalents, and restricted cash	717	(36)
Cash, cash equivalents and restricted cash at beginning of period	548	522
Cash, cash equivalents and restricted cash at end of period	1,265	486
Reconciliation of cash, cash equivalents and restricted cash as shown in the Condensed Consolidated Statements of Cash Flows
Cash and cash equivalents			$ 1,214	$ 509	$ 414
Restricted cash included in other assets			51	72	72
Total cash, cash equivalents and restricted cash	1,265	486	1,265	548	486	$ 522
Eliminations
Proceeds from Contributions from Parent		10
Net cash provided by (used in) operating activities	(1)	0
Investing activities
Expenditures for property, plant and equipment	0	0
Proceeds from sale of property, plant and equipment	0
Additions to capitalized software	0	0
Proceeds from (payments of) intercompany notes	(252)	(59)
Investments in equity affiliates		(10)
Business acquisitions, net	0	0
Net change in funds held for clients - investing	0	0
Increase (Decrease) in Client Funds Held	0	0
Other investing activities, net		0
Net Cash Provided by (Used in) Investing Activities	(252)	(69)
Financing activities
Short term borrowings, net	0	0
Payments on term credit facilities	0	0
Payments on revolving credit facilities	0	0
Borrowings on revolving credit facilities	0	0
Repurchases of Common Stock	0
Payments of Debt Issuance Costs	0
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	0
Proceeds from employee stock plans	0	0
Proceeds from (Payments for) Other Financing Activities	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	1
Borrowings (repayments) of intercompany notes	252	59
Tax withholding payments on behalf of employees	0	0
Net Cash Provided by (Used in) Financing Activities	253	69
Cash flows from discontinued operations
Net cash provided by (used in) operating activities	0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	0
Increase (decrease) in cash, cash equivalents, and restricted cash	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	0	0
Reconciliation of cash, cash equivalents and restricted cash as shown in the Condensed Consolidated Statements of Cash Flows
Cash and cash equivalents			0	0	0
Restricted cash included in other assets			0		0
Total cash, cash equivalents and restricted cash	0	0	0	0	0
Parent Issuer
Proceeds from Contributions from Parent		0
Net cash provided by (used in) operating activities	(67)	111
Investing activities
Expenditures for property, plant and equipment	(2)	(13)
Proceeds from sale of property, plant and equipment	7
Additions to capitalized software	(55)	(36)
Proceeds from (payments of) intercompany notes	242	29
Investments in equity affiliates		0
Business acquisitions, net	(6)	(6)
Net change in funds held for clients - investing	0	0
Increase (Decrease) in Client Funds Held	0	0
Other investing activities, net		3
Net Cash Provided by (Used in) Investing Activities	186	(23)
Financing activities
Short term borrowings, net	(2)	0
Payments on term credit facilities	(2)	(17)
Payments on revolving credit facilities	(430)	(375)
Borrowings on revolving credit facilities	1,310	330
Repurchases of Common Stock	(41)
Payments of Debt Issuance Costs	(1)
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	(6)
Proceeds from employee stock plans	3	4
Proceeds from (Payments for) Other Financing Activities	(2)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	0
Borrowings (repayments) of intercompany notes	0	0
Tax withholding payments on behalf of employees	(24)	(13)
Net Cash Provided by (Used in) Financing Activities	809	(71)
Cash flows from discontinued operations
Net cash provided by (used in) operating activities	3	(6)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	0
Increase (decrease) in cash, cash equivalents, and restricted cash	931	11
Cash, cash equivalents and restricted cash at beginning of period	15	11
Cash, cash equivalents and restricted cash at end of period	946	22
Reconciliation of cash, cash equivalents and restricted cash as shown in the Condensed Consolidated Statements of Cash Flows
Cash and cash equivalents			945	15	21
Restricted cash included in other assets			1		1
Total cash, cash equivalents and restricted cash	946	22	946	15	22
Guarantor Subsidiary
Proceeds from Contributions from Parent		(10)
Net cash provided by (used in) operating activities	(10)	(20)
Investing activities
Expenditures for property, plant and equipment	0	0
Proceeds from sale of property, plant and equipment	0
Additions to capitalized software	0	0
Proceeds from (payments of) intercompany notes	10	30
Investments in equity affiliates		0
Business acquisitions, net	0	0
Net change in funds held for clients - investing	0	0
Increase (Decrease) in Client Funds Held	0	0
Other investing activities, net		0
Net Cash Provided by (Used in) Investing Activities	10	30
Financing activities
Short term borrowings, net	0	0
Payments on term credit facilities	0	0
Payments on revolving credit facilities	0	0
Borrowings on revolving credit facilities	0	0
Repurchases of Common Stock	0
Payments of Debt Issuance Costs	0
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	0
Proceeds from employee stock plans	0	0
Proceeds from (Payments for) Other Financing Activities	0
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	0
Borrowings (repayments) of intercompany notes	0	0
Tax withholding payments on behalf of employees	0	0
Net Cash Provided by (Used in) Financing Activities	0	(10)
Cash flows from discontinued operations
Net cash provided by (used in) operating activities	0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	0
Increase (decrease) in cash, cash equivalents, and restricted cash	0	0
Cash, cash equivalents and restricted cash at beginning of period	3	3
Cash, cash equivalents and restricted cash at end of period	3	3
Reconciliation of cash, cash equivalents and restricted cash as shown in the Condensed Consolidated Statements of Cash Flows
Cash and cash equivalents			3	3	3
Restricted cash included in other assets			0		0
Total cash, cash equivalents and restricted cash	3	3	3	3	3
Non-Guarantor Subsidiaries
Proceeds from Contributions from Parent		0
Net cash provided by (used in) operating activities	139	(107)
Investing activities
Expenditures for property, plant and equipment	(8)	(9)
Proceeds from sale of property, plant and equipment	0
Additions to capitalized software	(14)	(7)
Proceeds from (payments of) intercompany notes	0	0
Investments in equity affiliates		10
Business acquisitions, net	(20)	0
Net change in funds held for clients - investing	0	0
Increase (Decrease) in Client Funds Held	12	17
Other investing activities, net		0
Net Cash Provided by (Used in) Investing Activities	(42)	(6)
Financing activities
Short term borrowings, net	(1)	(7)
Payments on term credit facilities	0	0
Payments on revolving credit facilities	(143)	0
Borrowings on revolving credit facilities	87	100
Repurchases of Common Stock	0
Payments of Debt Issuance Costs	0
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	0
Proceeds from employee stock plans	0	0
Proceeds from (Payments for) Other Financing Activities	(1)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	(1)
Borrowings (repayments) of intercompany notes	(252)	(59)
Tax withholding payments on behalf of employees	0	0
Net Cash Provided by (Used in) Financing Activities	(297)	65
Cash flows from discontinued operations
Net cash provided by (used in) operating activities	0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(14)	1
Increase (decrease) in cash, cash equivalents, and restricted cash	(214)	(47)
Cash, cash equivalents and restricted cash at beginning of period	530	508
Cash, cash equivalents and restricted cash at end of period	316	461
Reconciliation of cash, cash equivalents and restricted cash as shown in the Condensed Consolidated Statements of Cash Flows
Cash and cash equivalents			266	491	390
Restricted cash included in other assets			50		71
Total cash, cash equivalents and restricted cash	$ 316	$ 461	$ 316	$ 530	$ 461