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		Dec. 31, 2017	Dec. 31, 2016
Statement [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		$ 285,301	$ 278,197
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]	139,920	131,914
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	[1]	134,160	127,153
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		602	922
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		133,558	126,231
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],[2]	$ 5,760	$ 4,761

[1] Excludes loans that have completed the foreclosure or short sale process (i.e., involuntary prepayments).

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