Nature of Operations and Basis of Presentation - Components of Other (Income) Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other expense (income), net	$ 8	$ (6)	$ 104	$ (22)
Non-cash pre-tax settlement charge			113
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other components of net periodic benefit cost	(8)	(8)	88	(24)
Net loss from investments	16	2	16	2
Other expense (income), net	$ 8	$ (6)	$ 104	$ (22)