Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Flows from Operating Activities:
Net income (loss) including noncontrolling interests	$ 763	$ 554	$ (65)
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Reversal of) provision for loan losses	(202)	182	1,114
(Reversal of) provision for losses on off-balance sheet commitments	(29)	(14)	51
Depreciation, amortization and accretion, net	332	234	155
Stock-based compensation - restricted stock units	8	3	0
Deferred income taxes	138	84	(122)
Net gains on sales of securities	(58)	(105)	(24)
Net decrease (increase) in trading account assets	(136)	(274)	491
Net decrease (increase) in other assets	279	235	(765)
Net increase (decrease) in trading account liabilities	265	221	(496)
Net increase (decrease) in other liabilities	726	(149)	(614)
Loans originated for resale	(19)	(14)	(65)
Net proceeds from sale of loans originated for resale	22	5	48
Other, net	(236)	4	166
Total adjustments	1,090	412	(61)
Net cash provided by (used in) operating activities	1,853	966	(126)
Cash Flows from Investing Activities:
Proceeds from sales of securities available for sale	4,556	4,407	5,295
Proceeds from matured and called securities available for sale	5,758	9,611	2,537
Purchases of securities available for sale	(12,257)	(12,083)	(23,295)
Proceeds from matured securities held to maturity	157	14	8
Purchases of premises and equipment, net	(86)	(139)	(101)
Proceeds from sales of loans	223	528	110
Net decrease (increase) in loans	(5,801)	49	1,754
Proceeds from FDIC loss share agreements	134	165	0
Net cash acquired from (paid for) acquisitions	(10)	272	0
Other, net	(5)	(8)	(1)
Net cash provided by (used in) investing activities	(7,331)	2,816	(13,693)
Cash Flows from Financing Activities:
Net increase (decrease) in deposits	4,466	(11,452)	22,468
Net increase (decrease) in commercial paper and other short-term borrowings	2,289	(278)	(6,903)
Capital contribution from The Bank of Tokyo-Mitsubishi UFJ, Ltd. (BTMU)	618	0	2,000
Proceeds from issuance of long-term debt	2,000	2,400	1,625
Repayment of long-term debt	(888)	(1,520)	(1,650)
Other, net	(2)	3	2
Change in noncontrolling interests	16	13	(2)
Net cash provided by (used in) financing activities	8,499	(10,834)	17,540
Net change in cash and cash equivalents	3,021	(7,052)	3,721
Cash and cash equivalents at beginning of period	1,174	8,226	4,505
Cash and cash equivalents at end of period	4,195	1,174	8,226
Cash Paid During the Period For:
Interest	354	401	562
Income taxes, net	222	(9)	210
Acquisitions
Fair value of assets acquired	38	3,225	0
Fair value of liabilities assumed	15	3,497	0
Transfer of The Bank of Tokyo-Mitsubishi UFJ Trust Company (BTMUT) from BTMU:
Carrying value of assets transferred	372	0	0
Carrying value of liabilities transferred	207	0	0
Securities available for sale transferred to securities held to maturity	0	0	1,144
Net transfer of loans held for investment to loans held for sale	288	618	216
Transfer of loans held for investment to other real estate owned assets (OREO)	$ 169	$ 105	$ 66