Related party transactions with affiliated company - Additional Information (Detail) (USD $) In Millions, unless otherwise specified					9 Months Ended				9 Months Ended
	Sep. 30, 2014 Prlp2011 Holdings Llc Joint Venture [Member]	Sep. 30, 2011 Prlp2011 Holdings Llc Joint Venture [Member]	Sep. 30, 2014 PR Asset Portfolio 2013-1 International, LLC [Member]	Mar. 31, 2013 PR Asset Portfolio 2013-1 International, LLC [Member]	Sep. 30, 2014 E V E R T E C Inc [Member]	Sep. 30, 2013 E V E R T E C Inc [Member]	Sep. 30, 2014 Financial Standby Letter Of Credit Member	Dec. 31, 2013 Financial Standby Letter Of Credit Member	Sep. 30, 2014 Financial Standby Letter Of Credit Member E V E R T E C Inc [Member]	Dec. 31, 2013 Financial Standby Letter Of Credit Member E V E R T E C Inc [Member]
Related Party Transaction [Line Items]
Equity Method Investment Ownership Percentage	24.90%	24.90%	24.90%	24.90%	14.81%
Guarantee Obligations Current Carrying Value							$ 0.4	$ 0.4	$ 3.6	$ 3.6
Guarantee Obligations Term									5-year period
Equity method investments, distributions					$ 3.5	$ 2.7