Basis of Presentation and Accounting Policies - Schedule of Company's Reconciliation of Level 3 assets (Detail) (USD $) In Thousands, unless otherwise specified			6 Months Ended
Jun. 30, 2013 Investment Securities Available for Sale [Member]	Dec. 31, 2012 Investment Securities Available for Sale [Member]	Jun. 30, 2013 Impaired Loans Carried at Fair Value [Member]	Jun. 30, 2013 Other Real Estate Owned [Member]	Jun. 30, 2013 Covered Loans [Member]	Jun. 30, 2013 Covered Other Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance January 1, 2013	$ 2,000	$ 2,000	$ 52,514	$ 39,850	$ 507,712	$ 88,273
Total gains/(losses) included in net income				(409)		(3,191)
Purchases, sales, issuances, and settlements, net			(2,196)	(5,120)	(40,921)	(46,178)
Transfers in or out of Level 3			(5,564)	5,564	(23,274)	23,274
Ending balance June 30, 2013	$ 2,000	$ 2,000	$ 44,754	$ 39,885	$ 443,517	$ 62,178

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

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- Definition

Amount of purchases, (sales), issuances and (settlements) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph c

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

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- Definition

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

+ References

No definition available.

+ Details

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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

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