Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	$ 2,070	$ 2,436
Payments to Acquire Available-for-sale Securities	(5,853)	(8,657)
Proceeds from sales of available-for-sale securities	2,162	6,584
Proceeds from maturities and repayment of available-for-sale securities	1,230	1,536
Payments to Acquire Held-to-maturity Securities	(313)	(571)
Proceeds from Sale and Maturity of Held-to-maturity Securities	17	0
Payments to Acquire Loans Held-for-investment	1,817	2,442
Proceeds from Sale of Loans and Leases Held-for-investment	1,280	4,156
Originations and repayments of loans held-for-investment and other	(1,588)	(3,211)
Purchases of operating lease assets	(1,965)	(1,472)
Disposals of operating lease assets	3,043	3,047
Payments to Acquire Interest in Subsidiaries and Affiliates	0	288
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	474	482
Increase (Decrease) in Non marketable equity securities	107	(354)
Payments for (Proceeds from) Other Investing Activities	(93)	(69)
Net cash provided by investing activities	(3,316)	(1,259)
Proceeds from (Repayments of) Short-term Debt	(1,962)	(2,112)
Increase (Decrease) in Deposits	7,133	6,308
Proceeds from issuance of long-term debt	9,330	9,020
Repayments of long-term debt	(14,366)	(14,305)
Net Change in Debt, Intercompany	0	0
Payments for Repurchase of Redeemable Preferred Stock		696
Payments for Repurchase of Common Stock	(373)	(14)
Payments of Dividends	(75)	(30)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(313)	(1,829)
Effect of exchange-rate changes on cash and cash equivalents	2	3
Cash and Cash Equivalents, Period Increase (Decrease)	(1,557)	(649)
Cash and Cash Equivalents, at Carrying Value	5,934	6,380
Cash and Cash Equivalents, at Carrying Value	4,377	5,731
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	561	146
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	35	0
Proceeds from Sale of Loans and Leases Held-for-investment	67	0
Originations and repayments of loans held-for-investment and other	1,044	(834)
Purchases of operating lease assets	0	0
Disposals of operating lease assets	4	9
Payments to Acquire Interest in Subsidiaries and Affiliates		288
Proceeds from Contributions from Parent	(824)	(988)
Returns of contributed capital	838	1,971
Increase (Decrease) in Restricted Cash	(45)	1
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	(26)	(82)
Net cash provided by investing activities	2,888	(150)
Proceeds from (Repayments of) Short-term Debt	1,083	123
Increase (Decrease) in Deposits	(123)	(29)
Proceeds from issuance of long-term debt	353	1,115
Repayments of long-term debt	(3,323)	(596)
Net Change in Debt, Intercompany	(370)	(8)
Payments for Repurchase of Redeemable Preferred Stock		696
Payments for Repurchase of Common Stock	(373)	(14)
Payments of Dividends	(75)	(30)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(2,828)	(135)
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	621	(139)
Cash and Cash Equivalents, at Carrying Value	820	1,635
Cash and Cash Equivalents, at Carrying Value	1,441	1,496
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	0	0
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	0	0
Proceeds from Sale of Loans and Leases Held-for-investment	0	0
Originations and repayments of loans held-for-investment and other	0	0
Purchases of operating lease assets	0	0
Disposals of operating lease assets	0	0
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	8
Increase (Decrease) in Restricted Cash	0	0
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	0	0
Net cash provided by investing activities	0	8
Proceeds from (Repayments of) Short-term Debt	0	0
Increase (Decrease) in Deposits	0	0
Proceeds from issuance of long-term debt	0	0
Repayments of long-term debt	0	0
Net Change in Debt, Intercompany	0	0
Payments for Repurchase of Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	0	(8)
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	0	(8)
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	0	0
Cash and Cash Equivalents, at Carrying Value	0	0
Cash and Cash Equivalents, at Carrying Value	0	0
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	1,856	2,919
Payments to Acquire Available-for-sale Securities	(5,853)	(8,657)
Proceeds from sales of available-for-sale securities	2,162	6,584
Proceeds from maturities and repayment of available-for-sale securities	1,230	1,536
Payments to Acquire Held-to-maturity Securities	(313)	(571)
Proceeds from Sale and Maturity of Held-to-maturity Securities	17
Payments to Acquire Loans Held-for-investment	1,782	2,442
Proceeds from Sale of Loans and Leases Held-for-investment	1,213	4,156
Originations and repayments of loans held-for-investment and other	(676)	(2,377)
Purchases of operating lease assets	(1,965)	(1,472)
Disposals of operating lease assets	3,039	3,038
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	524	481
Increase (Decrease) in Non marketable equity securities	107	(354)
Payments for (Proceeds from) Other Investing Activities	24	13
Net cash provided by investing activities	(1,758)	(67)
Proceeds from (Repayments of) Short-term Debt	(3,045)	(2,235)
Increase (Decrease) in Deposits	7,256	6,337
Proceeds from issuance of long-term debt	7,016	7,905
Repayments of long-term debt	(11,043)	(13,709)
Net Change in Debt, Intercompany	(1,864)	(62)
Payments for Repurchase of Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	(1,266)	(2,600)
Capital contributions from parent	824	988
Net cash (used in) provided by financing activities	(2,122)	(3,376)
Effect of exchange-rate changes on cash and cash equivalents	2	3
Cash and Cash Equivalents, Period Increase (Decrease)	(2,022)	(521)
Cash and Cash Equivalents, at Carrying Value	5,515	5,595
Cash and Cash Equivalents, at Carrying Value	3,493	5,074
Affiliated Entity [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	0
Payments for (Proceeds from) Loans and Leases	0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	(1)
Payments for (Proceeds from) Loans and Leases	1,864	61
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	0
Payments for (Proceeds from) Loans and Leases	0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	(269)
Payments for (Proceeds from) Loans and Leases	246	(2)
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	(347)	(629)
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	0	0
Proceeds from Sale of Loans and Leases Held-for-investment	0	0
Originations and repayments of loans held-for-investment and other	(1,956)	0
Purchases of operating lease assets	0	0
Disposals of operating lease assets	0	0
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	824	988
Returns of contributed capital	(838)	(1,979)
Increase (Decrease) in Restricted Cash	(5)	0
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	(91)	0
Net cash provided by investing activities	(4,446)	(1,050)
Proceeds from (Repayments of) Short-term Debt	0	0
Increase (Decrease) in Deposits	0	0
Proceeds from issuance of long-term debt	1,961	0
Repayments of long-term debt	0	0
Net Change in Debt, Intercompany	2,234	70
Payments for Repurchase of Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	1,266	2,608
Capital contributions from parent	(824)	(988)
Net cash (used in) provided by financing activities	4,637	1,690
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	(156)	11
Cash and Cash Equivalents, at Carrying Value	(401)	(850)
Cash and Cash Equivalents, at Carrying Value	(557)	(839)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	270
Payments for (Proceeds from) Loans and Leases	$ (2,110)	$ (59)