Changes in Allowance for Loan Losses by Loan Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Allowance for loan losses:
Beginning balance	$ 70,143	$ 77,133	$ 70,898	$ 82,977
Provision for losses	4,609	5,556	14,029	16,775
Recoveries on loans	2,517	1,955	6,219	11,137
Loans charged off	(7,776)	(11,570)	(21,653)	(37,815)
Ending balance	69,493	73,074	69,493	73,074
Commercial
Allowance for loan losses:
Beginning balance	17,791	23,715	17,731	32,508
Provision for losses	5,431	(903)	10,333	(14,778)
Recoveries on loans	526	1,176	1,193	8,174
Loans charged off	(1,424)	(4,344)	(6,933)	(6,260)
Ending balance	22,324	19,644	22,324	19,644
Commercial Real Estate
Allowance for loan losses:
Beginning balance	35,133	38,668	37,919	36,341
Provision for losses	(879)	3,042	149	24,232
Recoveries on loans	1,598	378	3,462	1,244
Loans charged off	(4,439)	(5,003)	(10,117)	(24,732)
Ending balance	31,413	37,085	31,413	37,085
Consumer
Allowance for loan losses:
Beginning balance	2,431	2,859	2,902	3,622
Provision for losses	147	281	(14)	(187)
Recoveries on loans	219	163	595	781
Loans charged off	(168)	(266)	(854)	(1,179)
Ending balance	2,629	3,037	2,629	3,037
Residential
Allowance for loan losses:
Beginning balance	14,788	11,877	12,343	10,408
Provision for losses	(90)	3,142	3,565	7,601
Recoveries on loans	174	237	968	934
Loans charged off	(1,745)	(1,957)	(3,749)	(5,644)
Ending balance	13,127	13,299	13,127	13,299
Finance Lease
Allowance for loan losses:
Beginning balance		14	3	98
Provision for losses		(6)	(4)	(93)
Recoveries on loans		1	1	4
Ending balance		$ 9		$ 9

Reflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.

+ References+ Details

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

-Chapter V

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

+ Details

- Definition

The sum of the periodic provision charged to earnings, based on an assessment of uncollectibility from the counterparty on account of loan, lease or other credit losses, to reduce these accounts to the amount that approximates their net realizable value.

+ References+ Details