Portfolio Balances and Delinquency Balances Based on 90 days or more Past Due and Net Charge-Offs Related to Managed Portfolio Loans (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		$ 283,994		$ 285,301
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		2,708		2,590
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		81	$ 115
Commercial Portfolio Segment [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		75,324		75,477
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		271		247
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		17	50
Consumer Portfolio Segment [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		67,294		67,704
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		1,789		1,832
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		62	62
Loans and Finance Receivables [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		142,618		143,181
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		2,060		2,079
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		79	112
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		139,287		139,920
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		308		171
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		2	3
Loans [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	2,089		2,200
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	340		340
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		0	0
Commercial Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[2]	5,798		5,760
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	[2]	0		0
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		0	0
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		133,489		134,160
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		308		$ 171
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	[3]	$ 2	$ 3

[1] Comprised of unsecuritized loans the Company originated and sold to private investors with servicing rights retained. Net charge-offs on these loans are not presented in the table as the data is not reported to the Company by the private investors that own these related loans.

[2] Comprised of commercial mortgages sold through Fannie Mae, Freddie Mac, and Ginnie Mae securitizations, whereby servicing has been retained by the Company.

[3] Amounts associated with $541 million and $602 million of managed securitized loans at March 31, 2018 and December 31, 2017, respectively. Net charge-off data is not reported to the Company for the remaining balance of $132.9 billion and $133.6 billion of managed securitized loans at March 31, 2018 and December 31, 2017, respectively.