Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Dec. 31, 2019
Unconsolidated Assets
Interest Bearing Deposits in Banks	$ 15,366				$ 7,184
Securities Available for Sale	15,629				17,789
Loans held for investment	86,535				88,213
Other Assets	9,814				10,200
Total assets	167,350	[1]	$ 172,010	[1]	170,810
Unconsolidated Liabilities
Other Liabilities	3,211				2,837
Total liabilities	150,613				154,443
Unconsolidated VIEs
Unconsolidated Assets
Securities Available for Sale	27				27
Loans held for investment	242				232
Other Assets	2,231				2,197
Total assets	2,500				2,456
Unconsolidated Liabilities
Other Liabilities	191				152
Total liabilities	191				152
Maximum Exposure to Loss	2,606				2,557
Unconsolidated VIEs | LIHC investments
Variable Interest Entities
Liabilities Assumed	52		$ 94
Unconsolidated Assets
Securities Available for Sale	27				27
Loans held for investment	236				219
Other Assets	868				872
Total assets	1,131				1,118
Unconsolidated Liabilities
Other Liabilities	187				148
Total liabilities	187				148
Maximum Exposure to Loss	1,130				1,118
Unconsolidated VIEs | Leasing investments
Unconsolidated Assets
Securities Available for Sale	0				0
Loans held for investment	0				0
Other Assets	1,290				1,256
Total assets	1,290				1,256
Unconsolidated Liabilities
Other Liabilities	0				0
Total liabilities	0				0
Maximum Exposure to Loss	1,310				1,276
Unconsolidated VIEs | Other investments
Unconsolidated Assets
Securities Available for Sale	0				0
Loans held for investment	6				13
Other Assets	73				69
Total assets	79				82
Unconsolidated Liabilities
Other Liabilities	4				4
Total liabilities	4				4
Maximum Exposure to Loss	$ 166				$ 163

[1] As of and for the Three Months Ended June 30, 2020:(Dollars in millions) Regional Bank Global Corporate & Investment Banking - U.S. Transaction Banking MUSA Other MUFG Americas Holdings CorporationResults of operations Net interest income $500 $95 $46 $96 $50 $787Noninterest income 97 117 9 187 399 809Total revenue 597 212 55 283 449 1,596Noninterest expense 502 131 44 150 351 1,178(Reversal of) provision for credit losses 317 41 — — 3 361Income (loss) before income taxes and including noncontrolling interests (222) 4011133 9557Income tax expense (benefit) (1) (65) (5) — 34 75 39Net income (loss) including noncontrolling interests (157) 45 11 99 20 18Deduct: net (income) loss from noncontrolling interests — — — — 4 4Net income (loss) attributable to MUAH $(157) $45 $11 $99 $24 $22 Total assets, end of period $71,941 $21,735 $251 $27,881 $45,542 $167,350