Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractual principal and interest payments	$ 303	$ 331
Purchased impaired loans as a percentage of total assets	Less than 1% of the Company's assets	Less than 1% of the Company's assets
Loan delinquent period	90 days
Delinquency period for loan level collectability analysis consumer mortgage	More than 150 days
Residential Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans held for sale	292	401
Real Estate Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loans held for sale	$ 38	$ 68