Contingencies - Estimated Amounts of Regular, Discharge Payments Expected to Pay and Estimated Recoveries from Charged-off Loans (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	$ 54,040
Estimated Discharge Payments	72,005
Estimated Total Payments	126,045
Estimated Recoveries	(4,435)
2014 [Member]
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	5,429
Estimated Discharge Payments	0
Estimated Total Payments	5,429
Estimated Recoveries	(535)
2015 [Member]
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	14,730
Estimated Discharge Payments	0
Estimated Total Payments	14,730
Estimated Recoveries	(1,200)
2016 [Member]
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	16,787
Estimated Discharge Payments	0
Estimated Total Payments	16,787
Estimated Recoveries	(1,200)
2017 [Member]
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	17,094
Estimated Discharge Payments	0
Estimated Total Payments	17,094
Estimated Recoveries	(1,200)
2018 and Later [Member]
Summary Of Projections Of Estimated Payments And Recoveries [Line Items]
Estimated Regular Payments	0
Estimated Discharge Payments	72,005
Estimated Total Payments	72,005
Estimated Recoveries	$ (300)