Condensed MUFG Americas Holdings Corporation Unconsolidated Financial Statements (Parent Company) - Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income:
Total income	$ 5,278	$ 4,742	$ 4,375
Expense:
Other expense	3,782	3,747	3,256
Income (loss) before income taxes and equity in undistributed net income of subsidiaries	1,341	768	1,111
Income tax benefit	419	169	348
Equity in undistributed net income (loss) of subsidiaries:
Net Income Including Noncontrolling Interests	922	599	763
MUFG Americas Holdings Corporation
Income:
Rental Income	16	16	0
Interest income on advances to subsidiaries and deposits in bank	22	9	0
Total income	38	25	0
Expense:
Interest expense	75	65	21
Other expense	19	20	4
Total expense	94	85	25
Income (loss) before income taxes and equity in undistributed net income of subsidiaries	(56)	(60)	(25)
Income tax benefit	(22)	(24)	(10)
Income (loss) before equity in undistributed net income of subsidiaries	(34)	(36)	(15)
Equity in undistributed net income (loss) of subsidiaries:
Bank subsidiary	900	558	752
Nonbank subsidiaries	124	122	45
Net Income Including Noncontrolling Interests	$ 990	$ 644	$ 782