Impact on the results of operations of transactions between the Corporation and PRLP 2011 Holdings, LLC (Detail) (Interest Income Member, Prlp2011 Holdings Llc Joint Venture [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Scenario Actual Member
Related Party Transaction [Line Items]
Related Party Transaction Revenues From Transactions With Related Party	$ 619	$ 2,130
Scenario Consolidated [Member]
Related Party Transaction [Line Items]
Related Party Transaction Revenues From Transactions With Related Party	465	1,600
Eliminationsinterest [Member]
Related Party Transaction [Line Items]
Related Party Transaction Revenues From Transactions With Related Party	$ 154	$ 530