Summary of Significant Accounting Policies - Adjustments Made Due to ASU 2014-09 Impact on Income Statement (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	$ 572	$ 579	$ 1,166	$ 1,162
Cost of sales	(460)	(459)	(943)	(929)
Operating loss	(48)	$ (12)	(64)	$ (22)
Balances without adoption of ASC 606 \| ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	573		1,166
Cost of sales	(461)		(943)
Operating loss	(48)		$ (64)
Adjustments due to ASU 2014-09 / Effect of Changes \| ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	(1)
Cost of sales	$ 1

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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