Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net Income Attributable to MUAH	$ 573	$ 816	$ 647
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges		5	(8)
Net change in unrealized gains (losses) on investment securities		183	(487)
Foreign currency translation adjustment		(7)	(4)
Pension and other postretirement benefit adjustments		(286)	389
Total other comprehensive income (loss)	(23)	(105)	(110)
Comprehensive Income (Loss) Attributable to MUAH	550	711	537
Comprehensive loss from noncontrolling interests	(45)	(19)	(18)
Total Comprehensive Income (Loss)	$ 505	$ 692	$ 519