Business Combinations Allocation of Purchase Price (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Business Acquisition [Line Items]
Cash	$ 45
Trade accounts receivable	61
Property and equipment and other assets	20
Operating lease assets, net	44
Non-deductible goodwill	243
Current liabilities	65
Noncurrent liabilities	101
Purchase price, inclusive of contingent consideration	712
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tax-Deductible Goodwill	195
Linium
Business Acquisition [Line Items]
Cash	0
Trade accounts receivable	5
Property and equipment and other assets	1
Operating lease assets, net	0
Non-deductible goodwill	0
Current liabilities	2
Noncurrent liabilities	0
Purchase price, inclusive of contingent consideration	85
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tax-Deductible Goodwill	57
Magenic
Business Acquisition [Line Items]
Cash	13
Trade accounts receivable	17
Property and equipment and other assets	4
Operating lease assets, net	10
Non-deductible goodwill	34
Current liabilities	30
Noncurrent liabilities	7
Purchase price, inclusive of contingent consideration	246
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tax-Deductible Goodwill	114
ESG Mobility
Business Acquisition [Line Items]
Cash	28
Trade accounts receivable	24
Property and equipment and other assets	8
Operating lease assets, net	27
Non-deductible goodwill	31
Current liabilities	20
Noncurrent liabilities	65
Purchase price, inclusive of contingent consideration	134
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tax-Deductible Goodwill	24
Servian
Business Acquisition [Line Items]
Cash	4
Trade accounts receivable	15
Property and equipment and other assets	7
Operating lease assets, net	7
Non-deductible goodwill	178
Current liabilities	13
Noncurrent liabilities	29
Purchase price, inclusive of contingent consideration	247
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tax-Deductible Goodwill	0
Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets acquired	$ 267
Weighted Average Useful Life	10 years 2 months 12 days
Customer Relationships [Member] | Linium
Business Acquisition [Line Items]
Intangible assets acquired	$ 24
Customer Relationships [Member] | Magenic
Business Acquisition [Line Items]
Intangible assets acquired	90
Customer Relationships [Member] | ESG Mobility
Business Acquisition [Line Items]
Intangible assets acquired	77
Customer Relationships [Member] | Servian
Business Acquisition [Line Items]
Intangible assets acquired	76
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Intangible assets acquired	$ 3
Weighted Average Useful Life	4 years 1 month 6 days
Other Intangible Assets [Member] | Linium
Business Acquisition [Line Items]
Intangible assets acquired	$ 0
Other Intangible Assets [Member] | Magenic
Business Acquisition [Line Items]
Intangible assets acquired	1
Other Intangible Assets [Member] | ESG Mobility
Business Acquisition [Line Items]
Intangible assets acquired	0
Other Intangible Assets [Member] | Servian
Business Acquisition [Line Items]
Intangible assets acquired	$ 2