Segments (Results of Operations and Average Assets by Segment) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information
Bank premises and equipment held for sale	$ 27	$ 39	$ 81
Branch Banking
Segment Reporting Information
Impairment of Branches and Land	7	32	109
Commercial Banking | Operating lease equipment
Segment Reporting Information
Other Asset Impairment Charges	52	20	$ 36	[1],[2]
General Corporate and Other
Segment Reporting Information
Bank premises and equipment held for sale	$ 27	$ 39

[1] These rates reflect the floating rates as of December 31, 2017 .

[2] Includes impairment charges of $ 36 for operating lease equipment. For more information, refer to Note 8 .