Other Investments Other Investments (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	$ 0	$ 0
Equity Securities without Readily Determinable Fair Value, Amount	727,000,000		$ 250,000,000
Rivian
Schedule of Equity Method Investments [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount	$ 500,000,000