Transfers of Receivables - Assets and Liabilities of Securitizations (Details) - USD ($) $ in Millions | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | $ 9,079 | | $ 9,558 | | | |
Allowance for Credit Losses | 659 | $ 671 | 668 | $ 588 | $ 584 | $ 548 |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 143,207 | | | $ 134,993 | | |
Related Debt | 136,687 | | 137,828 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 3,079 | | 3,479 | | | |
Related Debt | 50,012 | | 46,437 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 3,100 | | 3,500 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 68,000 | | 68,000 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 67,800 | | 67,800 | | | |
Related Debt | 50,000 | | 46,400 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member] | Financing Receivable [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 2,500 | | 3,000 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 55,800 | | 56,500 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 55,600 | | 56,300 | | | |
Related Debt | 42,400 | | 39,200 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member] | Retail [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 2,000 | | 1,800 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 33,700 | | 32,600 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 33,500 | | 32,400 | | | |
Related Debt | 29,400 | | 27,700 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member] | Wholesale [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 500 | | 1,200 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 22,100 | | 23,900 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 22,100 | | 23,900 | | | |
Related Debt | 13,000 | | 11,500 | | | |
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member] | Net Investment in Operating Leases [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 600 | | 500 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 12,200 | | 11,500 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 12,200 | | 11,500 | | | |
Related Debt | 7,600 | | 7,200 | | | |
Consolidated Entities [Member] | Securitization Transactions [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 3,300 | | 3,800 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 73,800 | | 74,900 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 73,600 | | 74,700 | | | |
Related Debt | 55,100 | | 52,600 | | | |
Consolidated Entities [Member] | Securitization Transactions [Member] | Financing Receivable [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 2,700 | | 3,300 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 61,600 | | 63,400 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 61,400 | | 63,200 | | | |
Related Debt | 47,500 | | 45,400 | | | |
Consolidated Entities [Member] | Securitization Transactions [Member] | Retail [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 2,200 | | 2,100 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 39,300 | | 38,900 | | | |
Allowance for Credit Losses | 200 | | 200 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 39,100 | | 38,700 | | | |
Related Debt | 34,300 | | 33,400 | | | |
Consolidated Entities [Member] | Securitization Transactions [Member] | Wholesale [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 500 | | 1,200 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 22,300 | | 24,500 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 22,300 | | 24,500 | | | |
Related Debt | 13,200 | | 12,000 | | | |
Consolidated Entities [Member] | Securitization Transactions [Member] | Net Investment in Operating Leases [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 600 | | 500 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 12,200 | | 11,500 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 12,200 | | 11,500 | | | |
Related Debt | 7,600 | | 7,200 | | | |
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | Securitization Transactions [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 200 | | 300 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 5,800 | | 6,900 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 5,800 | | 6,900 | | | |
Related Debt | 5,100 | | 6,200 | | | |
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | Securitization Transactions [Member] | Financing Receivable [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 200 | | 300 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 5,800 | | 6,900 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 5,800 | | 6,900 | | | |
Related Debt | 5,100 | | 6,200 | | | |
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | Securitization Transactions [Member] | Retail [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 200 | | 300 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 5,600 | | 6,300 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 5,600 | | 6,300 | | | |
Related Debt | 4,900 | | 5,700 | | | |
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | Securitization Transactions [Member] | Wholesale [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 0 | | 0 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 200 | | 600 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 200 | | 600 | | | |
Related Debt | 200 | | 500 | | | |
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | Securitization Transactions [Member] | Net Investment in Operating Leases [Member] | | | | | | |
Securitization Transactions [Line Items] | | | | | | |
Cash and cash equivalents | 0 | | 0 | | | |
Finance Receivables and Net Investment in Operating Leases, Before Allowance for Credit Losses | 0 | | 0 | | | |
Allowance for Credit Losses | 0 | | 0 | | | |
Finance Receivables and Net Investment In Operating Leases, After Allowance for Credit Losses | 0 | | 0 | | | |
Related Debt | $ 0 | | $ 0 | | | |