Consolidated Statement of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Originations and repayments of loans held-for-investment and other	$ (1,063)	$ (8,826)	$ (9,344)
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss) Attributable to Parent	929	1,067	1,289
Depreciation, Amortization and Accretion, Net	1,859	2,382	2,801
Provision for Loan Losses Expensed Including Discontinued Operations	1,148	917	707
Gain Loss on Sales of Loans Net Including Discontinued Operations	(68)	(11)	(45)
Availableforsale Securities Gross Realized Gain Loss Excluding Otti Including Disc Ops	(102)	(185)	(155)
Gain (Loss) on Extinguishment of Debt	7	5	357
Payments for Origination and Purchases of Loans Held-for-sale	(414)	(141)	(1,770)
Proceeds from Sale of Loans Held-for-sale	310	240	1,658
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0	0	(452)
Increase (Decrease) in Deferred Income Taxes	534	458	565
Increase (Decrease) in Interest Payable, Net	24	1	(127)
Increase (Decrease) in Other Operating Assets	(153)	(120)	526
Increase (Decrease) in Other Operating Liabilities	(69)	(206)	(247)
Increase (Decrease) in Other Operating Assets and Liabilities, Net	74	160	4
Net Cash Provided by (Used in) Operating Activities	4,079	4,567	5,111
Net Cash (Used in) Provided by Investing Activities [Abstract]
Payments to Acquire Available-for-sale Securities	(11,234)	(16,031)	(12,250)
Proceeds from sales of available-for-sale securities	4,633	11,036	6,874
Proceeds from maturities and repayment of available-for-sale securities	2,899	3,379	4,255
Payments to Acquire Held-to-maturity Securities	(1,026)	(841)	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	68	0	0
Payments for (Proceeds from) Loans and Leases	(5,452)	(3,859)	(4,501)
Proceeds from Sale of Loans Held-for-investment	1,339	4,285	3,197
Purchases of operating lease assets	(4,052)	(3,274)	(4,685)
Disposals of operating lease assets	5,567	6,304	5,546
Payments to Acquire Interest in Subsidiaries and Affiliates	0	309	0
Proceeds from Divestiture of Businesses	0	0	1,049
Increase (Decrease) in Non marketable equity securities	(187)	(628)	(147)
Payments for (Proceeds from) Other Investing Activities	(219)	(306)	3
Net cash provided by investing activities	(8,727)	(9,070)	(10,003)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from (Repayments of) Short-term Debt	(1,263)	4,564	1,028
Increase (Decrease) in Deposits	14,172	12,508	8,247
Proceeds from issuance of long-term debt	17,969	14,155	30,665
Repayments of long-term debt	(27,908)	(26,412)	(31,350)
Payments for Repurchase of Redeemable Preferred Stock	0	696	559
Payments for Repurchase of Common Stock	(753)	(341)	(16)
Payments of Dividends	(184)	(108)	(2,571)
Net cash (used in) provided by financing activities	2,033	3,670	5,444
Effect of exchange-rate changes on cash and cash equivalents	3	1	(4)
Supplemental Cash Flow Information [Abstract]
Interest Paid	2,829	2,647	2,632
Income Taxes Paid	51	19	96
Held-to-maturity securities received in consideration for loans sold	56	0	0
Transfer of Portfolio Loans and Leases to Held-for-sale	1,339	4,282	1,311
Proceeds from sales and repayments of mortgage loans held-for-investment originally designated as held-for-sale	36	40	68
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and Cash Equivalents, at Carrying Value	4,252	5,934
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	5,269	7,881	8,713
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(2,612)	(832)	$ 548
Restricted Cash	$ 1,017	$ 1,947