Business Combinations - Additional Information (Detail) (USD $)	Jun. 30, 2014
Business Combinations [Abstract]
Loans acquired in the Charter One acquisition	$ 969,000,000
Deposits acquired in the Charter One acquisition	$ 4,800,000,000

The amount of financial liabilities assumed (as defined) which have been recognized as of the acquisition date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=39739317&loc=d3e4845-128472

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 55

-Paragraph 37

-URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financial Liability

-URI http://asc.fasb.org/extlink&oid=6513127

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinancialLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant