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		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		$ 299,181	$ 285,301
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		2,476	2,590
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		343	375
Commercial Portfolio Segment [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		80,940	75,477
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		175	247
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		107	127
Consumer Portfolio Segment [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		70,899	67,704
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		2,003	1,832
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		231	240
Loans and Finance Receivables [Member]
Principal Amount Outstanding of Loans Held-in-portfolio		151,839	143,181
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		2,178	2,079
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		338	367
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		146,208	139,920
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		146	171
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement		5	8
Loans [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	1,134	2,200
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	152	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]	6,399	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		139,809	134,160
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement		146	171
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	[3]	$ 5	$ 8

[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 $387 million and $602 million of managed securitized loans at December 31, 2018 and 2017, respectively. Net charge-off data is not reported to the Company for the remaining balance of $139.4 billion and $133.6 billion of managed securitized loans at December 31, 2018 and 2017, respectively.