Mortgage Servicing Rights - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Mortgage Loan Activity [Line Items]
Sale of 1-4 family mortgage loans to Federal National Mortgage Association (FNMA)	$ 99,458	$ 42,361	$ 87,932
Total servicing portfolio	361,200	325,800	327,400
Federal National Mortgage Association or (FNMA)
Mortgage Loan Activity [Line Items]
Sale of 1-4 family mortgage loans to Federal National Mortgage Association (FNMA)	$ 76,800	$ 40,100	$ 62,900

The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3536-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3461-108585

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