The amount of acquisition cost of a business combination allocated to property, plant and equipment to be used in ongoing operations.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 37

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_BusinessAcquisitionPurchasePriceAllocationPropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Subsequent Events - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended			1 Months Ended
	Sep. 30, 2012	Oct. 26, 2012 Subsequent Event Location	Oct. 26, 2012 Subsequent Event Augusta And Bangor Markets Location	Oct. 26, 2012 Subsequent Event Orono location
Subsequent Event [Line Items]
Number of branch banking locations to be acquired		15	3
Orono location branch reopen date, month and year				2012-12
Business acquisition, final settlement date	2013-01
Deposits		$ 290.5
Percentage of deposit premium		3.706%
Loans acquired		6.0
Fixed assets		2.0
Cost to acquire the branches and deposits, net of the divestiture		$ 17.4