Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income Attributable to MUAH	$ 295	[1]	$ 334	[2]	$ 524	[3]	$ 396	[4]
Other Comprehensive Income (Loss), Net of Tax:
Net change in unrealized gains (losses) on cash flow hedges	22		58		(8)		190
Net change in unrealized gains (losses) on investment securities	24		56		59		146
Foreign currency translation adjustment	2		1		3		5
Pension and other postretirement benefit adjustments	6		9		13		19
Other	0		2		0		0
Total other comprehensive income (loss)	54		126		67		360
Comprehensive Income (Loss) Attributable to MUAH	349		460		591		756
Comprehensive loss from noncontrolling interests	(10)		(11)		(15)		(23)
Total Comprehensive Income (Loss)	$ 339		$ 449		$ 576		$ 733

[1] The transferred IHC entities are not measured using a "market view" perspective.

[2] The transferred IHC entities are not measured using a "market view" perspective.

[3] The transferred IHC entities are not measured using a "market view" perspective.

[4] The transferred IHC entities are not measured using a "market view" perspective.