Premises and Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Rental expense for leased properties and equipment	$ 89us-gaap_LeaseAndRentalExpense	$ 78us-gaap_LeaseAndRentalExpense	$ 81us-gaap_LeaseAndRentalExpense
Lease termination charges included in rental expense	$ 10us-gaap_LossOnContractTermination

The loss recognized on termination of a contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 912

-SubTopic 275

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6471736&loc=d3e54681-109401

Name:	us-gaap_LossOnContractTermination
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration