Parent and Guarantor Condensed Consolidating Financial Statements (Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities			$ 3,133	$ 3,344
Purchases of equity securities			(301)	(652)
Proceeds from sales of equity securities			615	715
Purchases of available-for-sale securities			(11,214)	(5,669)
Proceeds from sales of available-for-sale securities			5,699	637
Proceeds from repayments of available-for-sale securities			3,246	2,509
Purchases of held-to-maturity securities			(514)	(436)
Proceeds from repayments of held-to-maturity securities			195	107
Purchases of finance receivables and loans held-for-investment			(3,322)	(4,778)
Proceeds from sales of finance receivables and loans initially held-for-investment			427	53
Originations and repayments of finance receivables and loans held-for-investment and other, net			3,069	(558)
Net change in intercompany loans	$ 10	$ 17	22	19
Purchases of operating lease assets			(2,937)	(2,991)
Disposals of operating lease assets			2,016	2,461
Capital contributions to subsidiaries			0	0
Returns of contributed capital			0	0
Net change in nonmarketable equity investments			179	(3)
Payments for (proceeds from) other, net			(306)	(241)
Net cash provided by (used in) investing activities			(3,148)	(8,846)
Net change in short-term borrowings			(4,652)	(4,074)
Net (decrease) increase in deposits			13,032	8,063
Proceeds from issuance of long-term debt			5,438	14,756
Repayments of long-term debt			(14,114)	(12,994)
Repurchase of common stock			(740)	(630)
Dividends paid			(206)	(179)
Capital contributions from parent			0	0
Net cash provided by (used in) financing activities			(1,242)	4,942
Effect of exchange-rate changes on cash and cash equivalents and restricted cash			2	(2)
Cash and cash equivalents	3,617	3,772	3,617	3,772	$ 4,537
Restricted Cash	754	935	754	935
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net decrease in cash and cash equivalents and restricted cash			(1,255)	(562)
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash	4,371	4,707	4,371	4,707
Cash and cash equivalents and restricted cash			5,626	5,269
Affiliated entity
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net change in intercompany investment securities			0	0
Net change in intercompany loans			0	0
Net Change in Debt, Intercompany			0	0
Dividends paid and returns of contributed capital, intercompany			0	0
Consolidating adjustments
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities			(3,072)	(4,489)
Purchases of equity securities			0	0
Proceeds from sales of equity securities			0	0
Purchases of available-for-sale securities			0	0
Proceeds from sales of available-for-sale securities			0	0
Proceeds from repayments of available-for-sale securities			0	0
Purchases of held-to-maturity securities			0	0
Proceeds from repayments of held-to-maturity securities			0	0
Purchases of finance receivables and loans held-for-investment			535	930
Proceeds from sales of finance receivables and loans initially held-for-investment			(535)	(930)
Originations and repayments of finance receivables and loans held-for-investment and other, net			6	0
Net change in intercompany loans	0	0	0	(28)
Purchases of operating lease assets			0	0
Disposals of operating lease assets			0	0
Capital contributions to subsidiaries			1	64
Returns of contributed capital			(29)	(222)
Net change in nonmarketable equity investments			0	0
Payments for (proceeds from) other, net			1	(1)
Net cash provided by (used in) investing activities			(1,087)	(249)
Net change in short-term borrowings			0	0
Net (decrease) increase in deposits			(756)	226
Proceeds from issuance of long-term debt			0	0
Repayments of long-term debt			0	0
Repurchase of common stock			0	0
Dividends paid			0	0
Capital contributions from parent			(1)	(64)
Net cash provided by (used in) financing activities			2,881	5,089
Effect of exchange-rate changes on cash and cash equivalents and restricted cash			0	0
Cash and cash equivalents	(3,048)	(1,482)	(3,048)	(1,482)	(1,770)
Restricted Cash	0	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net decrease in cash and cash equivalents and restricted cash			(1,278)	351
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash	(3,048)	(1,482)	(3,048)	(1,482)
Cash and cash equivalents and restricted cash			(1,770)	(1,833)
Consolidating adjustments | Affiliated entity
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net change in intercompany investment securities			(9)	(51)
Net change in intercompany loans			(1,057)	(39)
Net Change in Debt, Intercompany			542	216
Dividends paid and returns of contributed capital, intercompany			3,096	4,711
Parent
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities			1,157	1,417
Purchases of equity securities			0	0
Proceeds from sales of equity securities			0	0
Purchases of available-for-sale securities			0	0
Proceeds from sales of available-for-sale securities			0	0
Proceeds from repayments of available-for-sale securities			0	0
Purchases of held-to-maturity securities			0	0
Proceeds from repayments of held-to-maturity securities			0	0
Purchases of finance receivables and loans held-for-investment			0	(131)
Proceeds from sales of finance receivables and loans initially held-for-investment			548	983
Originations and repayments of finance receivables and loans held-for-investment and other, net			(519)	2,092
Net change in intercompany loans	1	16	4	44
Purchases of operating lease assets			0	0
Disposals of operating lease assets			3	9
Capital contributions to subsidiaries			(1)	(58)
Returns of contributed capital			29	222
Net change in nonmarketable equity investments			(12)	(14)
Payments for (proceeds from) other, net			(2)	1
Net cash provided by (used in) investing activities			807	3,149
Net change in short-term borrowings			24	(596)
Net (decrease) increase in deposits			0	(9)
Proceeds from issuance of long-term debt			771	51
Repayments of long-term debt			(1,304)	(3,393)
Repurchase of common stock			(740)	(630)
Dividends paid			(206)	(179)
Capital contributions from parent			0	0
Net cash provided by (used in) financing activities			(1,236)	(4,899)
Effect of exchange-rate changes on cash and cash equivalents and restricted cash			0	0
Cash and cash equivalents	2,067	968	2,067	968	1,309
Restricted Cash	59	94	59	94
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net decrease in cash and cash equivalents and restricted cash			728	(333)
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash	2,126	1,062	2,126	1,062
Cash and cash equivalents and restricted cash			1,398	1,395
Parent | Affiliated entity
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net change in intercompany investment securities			0	0
Net change in intercompany loans			761	45
Net Change in Debt, Intercompany			219	(143)
Dividends paid and returns of contributed capital, intercompany			0	0
Guarantors
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities			1,450	2,050
Purchases of equity securities			0	0
Proceeds from sales of equity securities			0	0
Purchases of available-for-sale securities			0	0
Proceeds from sales of available-for-sale securities			0	0
Proceeds from repayments of available-for-sale securities			0	0
Purchases of held-to-maturity securities			0	0
Proceeds from repayments of held-to-maturity securities			0	0
Purchases of finance receivables and loans held-for-investment			0	0
Proceeds from sales of finance receivables and loans initially held-for-investment			0	0
Originations and repayments of finance receivables and loans held-for-investment and other, net			0	0
Net change in intercompany loans	0	0	0	0
Purchases of operating lease assets			0	0
Disposals of operating lease assets			0	0
Capital contributions to subsidiaries			0	(6)
Returns of contributed capital			0	0
Net change in nonmarketable equity investments			0	0
Payments for (proceeds from) other, net			0	0
Net cash provided by (used in) investing activities			0	(6)
Net change in short-term borrowings			0	0
Net (decrease) increase in deposits			0	0
Proceeds from issuance of long-term debt			0	0
Repayments of long-term debt			0	0
Repurchase of common stock			0	0
Dividends paid			0	0
Capital contributions from parent			0	6
Net cash provided by (used in) financing activities			(1,450)	(2,044)
Effect of exchange-rate changes on cash and cash equivalents and restricted cash			0	0
Cash and cash equivalents	0	0	0	0	0
Restricted Cash	0	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net decrease in cash and cash equivalents and restricted cash			0	0
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash	0	0	0	0
Cash and cash equivalents and restricted cash			0	0
Guarantors | Affiliated entity
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net change in intercompany investment securities			0	0
Net change in intercompany loans			0	0
Net Change in Debt, Intercompany			0	0
Dividends paid and returns of contributed capital, intercompany			(1,450)	(2,050)
Nonguarantors
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities			3,598	4,366
Purchases of equity securities			(301)	(652)
Proceeds from sales of equity securities			615	715
Purchases of available-for-sale securities			(11,214)	(5,669)
Proceeds from sales of available-for-sale securities			5,699	637
Proceeds from repayments of available-for-sale securities			3,246	2,509
Purchases of held-to-maturity securities			(514)	(436)
Proceeds from repayments of held-to-maturity securities			195	107
Purchases of finance receivables and loans held-for-investment			(3,857)	(5,577)
Proceeds from sales of finance receivables and loans initially held-for-investment			414	0
Originations and repayments of finance receivables and loans held-for-investment and other, net			3,582	(2,650)
Net change in intercompany loans	9	1	18	3
Purchases of operating lease assets			(2,937)	(2,991)
Disposals of operating lease assets			2,013	2,452
Capital contributions to subsidiaries			0	0
Returns of contributed capital			0	0
Net change in nonmarketable equity investments			191	11
Payments for (proceeds from) other, net			(305)	(241)
Net cash provided by (used in) investing activities			(2,868)	(11,740)
Net change in short-term borrowings			(4,676)	(3,478)
Net (decrease) increase in deposits			13,788	7,846
Proceeds from issuance of long-term debt			4,667	14,705
Repayments of long-term debt			(12,810)	(9,601)
Repurchase of common stock			0	0
Dividends paid			0	0
Capital contributions from parent			1	58
Net cash provided by (used in) financing activities			(1,437)	6,796
Effect of exchange-rate changes on cash and cash equivalents and restricted cash			2	(2)
Cash and cash equivalents	4,598	4,286	4,598	4,286	$ 4,998
Restricted Cash	695	841	695	841
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net decrease in cash and cash equivalents and restricted cash			(705)	(580)
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash	$ 5,293	$ 5,127	5,293	5,127
Cash and cash equivalents and restricted cash			5,998	5,707
Nonguarantors | Affiliated entity
Parent and Guarantor Consolidating Statement of Cash Flows [Line Items]
Net change in intercompany investment securities			9	51
Net change in intercompany loans			296	(6)
Net Change in Debt, Intercompany			(761)	(73)
Dividends paid and returns of contributed capital, intercompany			$ (1,646)	$ (2,661)