Loans - Repricing Characteristics (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Expected To Be Collected Over One Year but Within Five Years	$ 36,185
Loans and Leases Receivable, Expected To Be Collected After Five Years	19,605
Variable Rate Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Expected To Be Collected Over One Year but Within Five Years	30,569
Loans and Leases Receivable, Expected To Be Collected After Five Years	15,384
Fixed Rate Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Expected To Be Collected Over One Year but Within Five Years	5,616
Loans and Leases Receivable, Expected To Be Collected After Five Years	$ 4,221