Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income Attributable to MUAH	$ 199	[1]	$ 344	[1]	$ 383	$ 510
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges	56		(8)		80	(66)
Net change in unrealized gains (losses) on investment securities	146		(41)		298	(231)
Foreign currency translation adjustment	0		0		0	(2)
Pension and other postretirement benefit adjustments	6		10		12	20
Other	0		0		1	(1)
Total other comprehensive income (loss)	208		(39)		391	(280)
Comprehensive Income (Loss) Attributable to MUAH	407		305		774	230
Comprehensive income (loss) from noncontrolling interests	(3)		(15)		(8)	(14)
Total Comprehensive Income (Loss)	$ 404		$ 290		$ 766	$ 216

[1] As of and for the Three Months Ended June 30, 2019:(Dollars in millions) Regional Bank U.S. Wholesale & Investment Banking Transaction Banking MUSA Other MUFG Americas Holdings CorporationResults of operations Net interest income $573 $116 $69 $37 $(18) $777Noninterest income 118 79 14 85 353 649Total revenue 691 195 83 122 335 1,426Noninterest expense 538 113 57 113 333 1,154(Reversal of) provision for credit losses 32 27 — — (3) 56Income (loss) before income taxes and including noncontrolling interests 121 55269 5216Income tax expense (benefit) (1) 20 (4) 7 2 (5) 20Net income (loss) including noncontrolling interests 101 59 19 7 10 196Deduct: net (income) loss from noncontrolling interests — — — — 3 3Net income (loss) attributable to MUAH $101 $59 $19 $7 $13 $199 Total assets, end of period $75,858 $20,331 $911 $35,131 $39,779 $172,010