Certain Transfers of Financial Assets and Variable Interest Entities Portfolio Balances and Delinquency Balances Based on 90 days or more Past Due and Net Charge-Offs Related to Managed Portfolio Loans (Additional Information) (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		$ 300,875	$ 299,181
Asset-backed Securities, Securitized Loans and Receivables [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		141,906	146,208
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		134,515	139,809
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | STI Sponsored Securitizations [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		212	387
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Managed Securitized Loans [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		134,300	139,400
Commercial Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	$ 7,391	$ 6,399

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