Financial Services Finance Receivables - Credit Quality (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	$ 104,439	$ 96,674	$ 95,642
Consumer [Member]
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	$ 72,316	65,338	65,109
Consumer [Member] | Minimum [Member] | Special Mention [Member]
Credit quality [Line Items]
Finance Receivables Credit Quality Ratings Term Range	61 days
Consumer [Member] | Minimum [Member] | Substandard [Member]
Credit quality [Line Items]
Finance Receivables Credit Quality Ratings Term Range	120 days
Consumer [Member] | Maximum [Member] | Pass [Member]
Credit quality [Line Items]
Finance Receivables Credit Quality Ratings Term Range	60 days
Consumer [Member] | Maximum [Member] | Special Mention [Member]
Credit quality [Line Items]
Finance Receivables Credit Quality Ratings Term Range	120 days
Non-consumer [Member]
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	$ 32,123	31,336	$ 30,533
Non-consumer [Member] | Dealer financing [Member]
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	32,123	31,336
Non-consumer [Member] | Dealer financing [Member] | Group I
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	24,911	24,315
Non-consumer [Member] | Dealer financing [Member] | Group II
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	5,581	5,552
Non-consumer [Member] | Dealer financing [Member] | Group III
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	1,479	1,376
Non-consumer [Member] | Dealer financing [Member] | Group IV
Credit quality [Line Items]
Financing Receivable By Credit Quality Indicator	$ 152	$ 93