Parent Company (Details 1) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 32,927	$ 25,208	$ 22,762	$ 22,288
Investment securities	3,159	3,157	3,759
Accounts receivable, less reserves	53,526	46,841
Premises and equipment, less accumulated depreciation	4,329	4,433
Other assets	9,755	10,561
Total assets	181,159	158,893	161,000
Liabilities and Shareholders' Equity
Long-term debt	55,804	46,990
Total liabilities	162,932	138,392
Shareholders' Equity
Preferred shares	0	0
Common shares	172	181
Additional paid-in capital	12,210	12,733
Retained earnings	8,273	10,371
Accumulated other comprehensive loss	(2,428)	(2,784)
Total shareholders' equity	18,227	20,501	20,673	20,673
Total liabilities and shareholders' equity	181,159	158,893
Parent Company Details (Textuals) [Abstract]
Premises and equipment, accumulated depreciation	5,455	5,145
Parent Company [Member]
Assets
Cash and cash equivalents	4,726	5,229	$ 6,400	$ 8,824
Investment securities	1	1
Equity in net assets of subsidiaries and affiliates	18,191	20,522
Accounts receivable, less reserves	103	513
Premises and equipment, less accumulated depreciation	5	30
Loans to subsidiaries and affiliates	11,664	7,620
Due from subsidiaries and affiliates	1,962	867
Other assets	252	277
Total assets	36,904	35,059
Liabilities and Shareholders' Equity
Accounts payable and other liabilities	3,076	1,531
Due to subsidiaries and affiliates	175	619
Short-term debt of subsidiaries and affiliates	2,731	4,044
Long-term debt	12,695	8,364
Total liabilities	18,677	14,558
Shareholders' Equity
Preferred shares	0	0
Common shares	172	181
Additional paid-in capital	12,210	12,733
Retained earnings	8,273	10,371
Accumulated other comprehensive loss	(2,428)	(2,784)
Total shareholders' equity	18,227	20,501
Total liabilities and shareholders' equity	36,904	35,059
Parent Company Details (Textuals) [Abstract]
Premises and equipment, accumulated depreciation	$ 9	$ 96