The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Goodwill and Other Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Impairment of goodwill (A and O)	$ 0		$ 0	$ 719,000,000	$ 0
Amortization of intangible assets			81,000,000	71,000,000	$ 65,000,000
Minimum
Goodwill [Line Items]
Expected amortization for the year 2019			63,000,000
Expected amortization for the year 2020			63,000,000
Expected amortization for the year 2021			63,000,000
Expected amortization for the year 2022			63,000,000
Expected amortization for the year 2023			63,000,000
Maximum
Goodwill [Line Items]
Expected amortization for the year 2019			70,000,000
Expected amortization for the year 2020			70,000,000
Expected amortization for the year 2021			70,000,000
Expected amortization for the year 2022			70,000,000
Expected amortization for the year 2023			$ 70,000,000
Engineered Products and Solutions
Goodwill [Line Items]
Impairment of goodwill (A and O)		$ 719,000,000		$ 719,000,000