Fair Value Measurements - Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Level 2 [Member]	Sep. 30, 2013 Level 2 [Member]	Sep. 30, 2014 Level 3 [Member]	Sep. 30, 2013 Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	$ 51,103	$ 48,462	$ 0	$ 13,870	$ 2,944	$ 4,430
Specific valuation allowance allocations	(2,189)	(6,926)	0	(2,098)	(1,275)	(2,370)
Loans Receivable, Fair Value Disclosure			$ 0	$ 11,772	$ 1,669	$ 2,060