Asset Quality - Summary of Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 891	$ 874	$ 882	$ 824
Charge-offs	(81)	(61)	(250)	(200)
Recoveries	41	14	80	54
Provision for loan and lease losses from continuing operations	51	59	180	200
Ending balance	898	883	898	883
Continuing Operations [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	870	854	858	796
Charge-offs	(71)	(55)	(230)	(179)
Recoveries	39	11	74	46
Net loans and leases charged off	(32)	(44)	(156)	(133)
Provision for loan and lease losses from continuing operations	42	56	178	203
Foreign currency translation adjustment	0	1	0	1
Ending balance	$ 880	$ 865	$ 880	$ 865