Fair Value Measurements Changes in Fair Value Level 3 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 5	$ 10	$ 9
Inventory Write-down		8
Impairment of Long-Lived Assets to be Disposed of		68
Level 3 | Recurring measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset measured on a recurring basis	372	278	$ 211
Fair value, measurement with unobservable inputs reconciliation, recurring basis, assets, unrealized gain (loss)	95	67
Fair value, measurement with unobservable inputs reconciliation, recurring basis, assets, other	(1)	0
Equity securities | Recurring measurement | Holding Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset measured on a recurring basis	$ 369	$ 274