Mortgage Servicing Rights - Activity in Valuation Allowance for Mortgage Servicing Rights (Detail) (Mortgage Servicing Rights [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Mortgage Servicing Rights [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance, beginning of period	$ (243)	$ (249)	$ (250)	$ (497)
Additions	0	0	0	0
Reductions	243	0	250	248
Direct write-downs	0	0	0	0
Valuation allowance, end of period	$ 0	$ (249)	$ 0	$ (249)

Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

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