Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income Attributable to MUAH	$ 49	$ 137
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges	135	52
Net change in unrealized gains (losses) on investment securities	91	73
Foreign currency translation adjustment	4	(7)
Pension and other postretirement benefit adjustments	10	14
Other Comprehensive Income Other, Net of Tax, Portion Attributable to Parent	(1)	0
Total other comprehensive income (loss)	239	132
Comprehensive Income (Loss) Attributable to MUAH	288	269
Comprehensive loss from noncontrolling interests	(12)	(5)
Total Comprehensive Income (Loss)	$ 276	$ 264