Interest-bearing Time Deposits in Banks and Securities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014 Investment	Jun. 30, 2013	Jun. 30, 2014 Investment	Jun. 30, 2013	Dec. 31, 2013
Interest Bearing Time Deposits In Banks And Securities [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	$ 24,188,000	$ 39,350,000	$ 24,188,000	$ 39,350,000	$ 31,917,000
Time deposits with balances greater than $100,000	21,909,000		21,909,000		29,002,000
Time deposits balances			100,000		100,000
Held-to-maturity securities	568,000	886,000	568,000	886,000	684,000
Number of investment positions	195		195
Securities pledged as collateral	1,415,104,000		1,415,104,000
Sales and calls of investment securities available-for-sale	541,000	66,128,000	1,445,000	71,355,000
Gross realized gains from security sales and calls	0	34,000	1,000	257,000
Gross realized losses from security sales and calls	$ 1,000	$ 1,000	$ 6,000	$ 2,000
Minimum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years			1 year
Maximum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years			2 years