Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income Attributable to MUAH	$ 990	$ 644	$ 782
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges	(115)	12	23
Net change in unrealized gains (losses) on investment securities	(56)	(6)	183
Foreign currency translation adjustment	2	(14)	(5)
Pension and other postretirement benefit adjustments	23	(13)	(285)
Total other comprehensive income (loss)	(146)	(21)	(84)
Comprehensive Income (Loss) Attributable to MUAH	844	623	698
Comprehensive loss from noncontrolling interests	(68)	(45)	(19)
Total Comprehensive Income (Loss)	$ 776	$ 578	$ 679