Loans - Repricing Characteristics (Details) $ in Millions	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Due Over 1 But Within 5 Years	$ 36,259
Loans Due Over 5 Years	20,294
Receivables at predetermined interest rates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Due Over 1 But Within 5 Years	4,606
Loans Due Over 5 Years	4,750
Receivables at floating or adjustable rates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Due Over 1 But Within 5 Years	31,653
Loans Due Over 5 Years	$ 15,544