Composition of loans held-in-portfolio-noncovered loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	$ 19,082,387		$ 24,951,299		$ 25,406,339
Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio			786,765		911,070
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio			6,691,414		6,143,158
Finance Leases Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio			548,706		565,881
Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio			648,409		898,772
Consumer Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	3,741,578		3,789,936		3,777,043
Non-covered loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	20,478,674	[1]	20,602,596	[1]
Non-covered loans | Commercial Multi Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	802,286		808,933
Non-covered loans | Commercial Real Estate Non Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	2,641,361		2,665,499
Non-covered loans | Commercial Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	2,665,551		2,817,266
Non-covered loans | Commercial And Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	3,759,044		3,681,629
Non-covered loans | Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	236,579		239,939
Non-covered loans | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	5,591,745		5,518,460
Non-covered loans | Finance Leases Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	543,314		548,706
Non-covered loans | Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	603,874	[2]	648,409	[2]
Non-covered loans | Consumer Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	3,634,920		3,673,755		3,625,286
Non-covered loans | Consumer Portfolio Segment Member | Consumer Credit Card Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	1,204,551		1,230,029
Non-covered loans | Consumer Portfolio Segment Member | Home Equity Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	542,249		557,894
Non-covered loans | Consumer Portfolio Segment Member | Personal [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	1,119,335		1,130,593
Non-covered loans | Consumer Portfolio Segment Member | Consumer Loans Auto Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	533,575		518,476
Non-covered loans | Consumer Portfolio Segment Member | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio	$ 235,210		$ 236,763

[1] Non-covered loans held-in-portfolio at March 31, 2012 are net of $99 million in unearned income and exclude $362 million in loans held-for-sale. (December 31, 2011 - $101 million in unearned income and $363 million in loans held-for-sale.)

[2] The legacy portfolio is comprised of commercial loans, construction loans and lease financings related to certain lending products exited by the Corporation as part of restructuring efforts carried out in prior years at the BPNA reportable segment.