Note Related party transactions (Impact on the results of operations of transactions between the Corporation and PRLP 2011 Holdings, LLC) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans \| PRLP 2011 Holding, LLC
Related Party Transaction [Line Items]
Interest Income Related Party	$ 11	$ 189	$ 425

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration