Fair Values of Financial Instruments - Narrative (Detail) (USD $)			12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Significant Unobservable Inputs (Level 3)	Dec. 31, 2013 Significant Unobservable Inputs (Level 3) Corporate Bonds and Notes	Dec. 31, 2013 Significant Unobservable Inputs (Level 3) Available for Sale Securities	Dec. 31, 2013 Significant Unobservable Inputs (Level 3) Held to Maturity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 537,848,000	$ 498,104,000		$ 6,400,000
Investment securities available for sale	536,201,000	513,343,000		2,700,000
Other-than-temporary impairment ("OTTI") loss			1,400,000
Transfer between Levels 1, 2 and 3					$ 350,000	$ (16,784,000)