Fair Value Measurement - Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified																			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Sep. 30, 2014 Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Impaired Originated & PNCI loans [Member]	Sep. 30, 2013 Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Foreclosed assets [Member]	Dec. 31, 2013 Foreclosed assets [Member]	Sep. 30, 2013 Foreclosed assets [Member]	Sep. 30, 2014 Level 3 [Member]	Dec. 31, 2013 Level 3 [Member]	Sep. 30, 2013 Level 3 [Member]	Sep. 30, 2014 Level 3 [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2013 Level 3 [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Foreclosed assets [Member]	Dec. 31, 2013 Level 3 [Member] Foreclosed assets [Member]	Sep. 30, 2013 Level 3 [Member] Foreclosed assets [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Minimum [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Minimum [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Minimum [Member] Foreclosed assets [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Minimum [Member] Foreclosed assets [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Maximum [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Maximum [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Maximum [Member] Foreclosed assets [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Maximum [Member] Foreclosed assets [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Weighted Average [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Weighted Average [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Sales comparison approach [Member] Weighted Average [Member] Foreclosed assets [Member]	Dec. 31, 2013 Level 3 [Member] Sales comparison approach [Member] Weighted Average [Member] Foreclosed assets [Member]	Sep. 30, 2014 Level 3 [Member] Income approach [Member] Minimum [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Income approach [Member] Minimum [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Income approach [Member] Maximum [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Income approach [Member] Maximum [Member] Impaired Originated & PNCI loans [Member]	Sep. 30, 2014 Level 3 [Member] Income approach [Member] Weighted Average [Member] Impaired Originated & PNCI loans [Member]	Dec. 31, 2013 Level 3 [Member] Income approach [Member] Weighted Average [Member] Impaired Originated & PNCI loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 6,102	$ 21,282	$ 24,687	$ 3,090	$ 20,334	$ 22,638	$ 3,012	$ 948	$ 2,049	$ 6,102	$ 21,282	$ 24,687	$ 3,090	$ 20,334	$ 22,638	$ 3,012	$ 948	$ 2,049
Adjustment for differences between comparable sales																			(5.00%)	(5.00%)	(5.00%)	(6.50%)	(39.00%)	(56.40%)	(28.60%)	(16.70%)	(9.00%)	(10.40%)	(7.70%)	(8.90%)
Capitalization rate																															9.09%	7.75%	9.25%	9.25%	9.23%	8.91%