Assets Acquired in FDIC-Assisted Acquisitions - Additional Information (Detail) $ in Thousands	6 Months Ended	34 Months Ended
Jun. 30, 2015 USD ($)	Jul. 31, 2012 Acquisition	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2013 USD ($)
Business Combinations [Abstract]
Number of FDIC-assisted acquisitions participation \| Acquisition		10
FDIC loss-share receivable	$ 14,957		$ 31,351	$ 49,180	$ 65,441
Federal funds purchased and securities sold under agreements to repurchase	13,400
Business acquisition, Charge-offs and expenses	8,900
Clawback liability	$ 7,300		$ 6,200	$ 5,200

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration