Note Related party transactions (Impact on the results of operations of transactions between the Corporation and PRLP 2011 Holdings, LLC) (Detail) - USD ($)	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Loans \| PRLP 2011 Holding, LLC
Related Party Transaction [Line Items]
Interest Income Related Party	$ 0	$ 11

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.

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