Fair Value Measurements - Long-lived Assets Measured at Fair Value on Non-recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2017	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment losses			$ 0	$ (234)
Intangible assets, net, Impairment losses			0	(12)
Goodwill, Impairment losses			0	234
Intangible assets, net, Impairment losses			0	12
Fair Value Measurements Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair value measurement	$ 292		291	292
Intangible assets, net, Fair value measurement	122		$ 102	$ 122
M A C O M Technology Solutions Holdings Inc | Customer Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets, net, Impairment losses		$ (12)
Intangible assets, net, Impairment losses		$ 12
VNBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment losses	(234)
Goodwill, Impairment losses	$ 234