Changes in the Allowance for Loan and Lease Losses for the Previous Five Quarters (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 53,645	$ 57,235	$ 57,249	$ 57,811	$ 56,642	$ 57,235	$ 59,311	$ 59,311
Provision for loan and lease losses - uncovered	5,756	647	9,741	6,287	6,158	6,403	17,536	33,564
Loans charged off	(6,232)	(4,601)	(10,285)	(8,124)	(5,457)	(10,833)	(19,942)	(38,351)
Recoveries	502	364	530	1,275	468	866	906	2,711
Balance at end of period	$ 53,671	$ 53,645	$ 57,235	$ 57,249	$ 57,811	$ 53,671	$ 57,811	$ 57,235
Allowance for loan and lease losses to total ending loans	1.92%	1.93%	2.03%	2.07%	2.07%	1.92%	2.07%	2.03%

Reflects a reduction in bad debt expense attributable to collections of loans and lease receivables which had previously been fully or partially charged off as bad debts.

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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.

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- Definition

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.

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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

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- Definition

The sum of the periodic provision charged to operations, based on an assessment of the uncollectibility of the loan and lease portfolio, the offset to which is either added to or deducted from the allowance account for the purpose of reducing loan receivable and leases to an amount that approximates their net realizable value (the amount expected to be collected).

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