Operating Lease Equipment (Additional Information) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating Lease Equipment
Other Asset Impairment Charges		$ (19)	$ (5)	[1]
Operating lease equipment | Commercial Banking
Operating Lease Equipment
Other Asset Impairment Charges	$ 5	$ 31	$ 5

[1] Net tax deficiencies of $ 6 were reclassified from capital surplus to applicable income tax expense for the six months ended June 30, 2016, related to the early adoption of ASU 2016-09 during the fourth quarter of 2016, with an effective date of January 1, 2016.