The allowance for loan and lease losses represents the reserve to cover probable credit losses related to specifically identified loans and leases, as well as probable credit losses inherent in the remainder of the loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for loan losses in connection with business combinations determined to be appropriate.

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

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

Reference 3: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: 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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph d

Reference 6: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 7: 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

+ Details

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Significant Accounting Policies [Line Items]
Weighted average quarterly median volatility assumption used for warrant valuation	52.50%	50.70%
Risk-free interest rate used for warrant	0.40%	1.00%
Carrying value of impaired loans	$ 36,617	$ 39,426
Allowance for loan losses	89,947	82,627	72,450
Troubled Debt Restructuring
Significant Accounting Policies [Line Items]
Carrying value of impaired loans	5,300
Allowance for loan losses	$ 1,300
Investments in limited partnerships \| Lower Limit
Significant Accounting Policies [Line Items]
Percentage of voting interest held by the company for investments accounted for under the equity method	5.00%
Investments in limited partnerships \| Upper Limit
Significant Accounting Policies [Line Items]
Percentage of voting interest held by the company for investments accounted for under the equity method	50.00%
Percentage of ownership interest held by the company for investments accounted for under the cost method	5.00%
Privately Held Companies \| Lower Limit
Significant Accounting Policies [Line Items]
Percentage of voting interest held by the company for investments accounted for under the equity method	20.00%
Privately Held Companies \| Upper Limit
Significant Accounting Policies [Line Items]
Percentage of voting interest held by the company for investments accounted for under the equity method	50.00%
Percentage of ownership interest held by the company for investments accounted for under the cost method	20.00%