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		Mar. 31, 2018	Dec. 31, 2017
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		$ 283,994	$ 285,301
Asset-backed Securities, Securitized Loans and Receivables [Member]
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		139,287	139,920
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		133,489	134,160
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		541	602
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		132,948	133,558
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]	$ 5,798	$ 5,760

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