Changes in the Corporation's liability of estimated losses from credit recourses agreements (Detail) (Financial Guarantee Member, USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financial Guarantee Member
Guarantor Obligations [Line Items]
Balance as of beginning of period	$ 45,809	$ 47,983	$ 41,463	$ 51,673
Provision	7,984	6,688	19,026	10,785
Net charge-offs / terminations	(5,901)	(8,779)	(12,597)	(16,566)
Balance as of end of period	$ 47,892	$ 45,892	$ 47,892	$ 45,892