Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net (Loss) Income Attributable to MUAH	$ (1,372)	[1]	$ 306	[1]	$ (989)	$ 816
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges	50		8		130	(58)
Net change in unrealized gains (losses) on investment securities	53		(46)		351	(277)
Foreign currency translation adjustment	0		0		0	(2)
Pension and other postretirement benefit adjustments	7		10		19	30
Other	0		0		1	(1)
Total other comprehensive income (loss)	110		(28)		501	(308)
Comprehensive Income (Loss) Attributable to MUAH	(1,262)		278		(488)	508
Comprehensive income (loss) from noncontrolling interests	(4)		(6)		(12)	(20)
Total Comprehensive Income (Loss)	$ (1,266)		$ 272		$ (500)	$ 488

[1] As of and for the Three Months Ended September 30, 2019:(Dollars in millions) Regional Bank Global Corporate & Investment Banking - U.S. Transaction Banking MUSA Other MUFG Americas Holdings CorporationResults of operations Net interest income $582 $104 $61 $39 $(32) $754Noninterest income 127 87 14 111 378 717Total revenue 709 191 75 150 346 1,471Noninterest expense 532 116 59 119 1,944 2,770(Reversal of) provision for credit losses 72 24 — — (1) 95Income (loss) before income taxes and including noncontrolling interests 105 511631 (1,597)(1,394)Income tax expense (benefit) (1) 19 (5) 10 7 (49) (18)Net income (loss) including noncontrolling interests 86 56 6 24 (1,548) (1,376)Deduct: net (income) loss from noncontrolling interests — — — — 4 4Net income (loss) attributable to MUAH $86 $56 $6 $24 $(1,544) $(1,372) Total assets, end of period $75,446 $20,820 $971 $35,199 $40,797 $173,233