Fair Value Measurements - Narrative (Details)	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2018 contract	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of earn out liability	$ 14,000,000				$ 14,000,000
Other operating income from earn out liability adjustment					13,000,000
Fair value of contingent consideration				$ 0
Goodwill, impairment charge				0	234,000,000	$ 0
Foreign exchange swap | Maturity Beyond Six Months
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of foreign currency derivatives held | contract			0
Foreign exchange forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	67,000,000			103,000,000	67,000,000
Derivative liability	1,000,000			1,000,000	1,000,000
Maximum | Foreign exchange swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of swap contracts			6 months
Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments				$ 8,000,000			$ 15,000,000
VNBS | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment charge	$ 234,000,000
Customer Contracts | M A C O M Technology Solutions Holdings Inc
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of finite lived intangible assets					$ 12,000,000
Customer Contracts | M A C O M Technology Solutions Holdings Inc | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of finite lived intangible assets		$ 12,000,000