FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Securities available for sale
Investment securities available for sale	$ 1,977,137	$ 1,978,282
Derivatives, included in assets:
Derivatives, included in assets	102	394
Derivatives, included in liabilities:
Derivatives, included in liabilities	2,911	4,023
Forward Contracts [Member]
Derivatives, included in assets:
Derivatives, included in assets	17	174
Derivatives, included in liabilities:
Derivatives, included in liabilities	16	0
Equity Securities [Member]
Securities available for sale
Investment securities available for sale	14	33
U S Treasury Securities [Member]
Securities available for sale
Investment securities available for sale	7,498	7,499
Us Government Agencies Debt Securities Noncallable [Member]
Securities available for sale
Investment securities available for sale	220,856	200,903
Us Government Agencies Debt Securities Callable [Member]
Securities available for sale
Investment securities available for sale	1,666,264	1,677,651
US States And Political Subdivisions Member [Member]
Securities available for sale
Investment securities available for sale	46,389	51,330
Private Label Mbs [Member]
Securities available for sale
Investment securities available for sale	36,116	40,866
Interest Rate Cap [Member] | Purchase
Derivatives, included in assets:
Derivatives, included in assets	18	58
Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Derivatives, included in liabilities	18	58
Interest Rate Swap [Member]
Derivatives, included in assets:
Derivatives, included in assets	67	162
Derivatives, included in liabilities:
Derivatives, included in liabilities	2,877	3,965
Fair Value Inputs Level 1 [Member] | Forward Contracts [Member]
Derivatives, included in assets:
Derivatives, included in assets	0	0
Derivatives, included in liabilities:
Derivatives, included in liabilities	0	0
Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Securities available for sale
Investment securities available for sale	14	33
Fair Value Inputs Level 1 [Member] | U S Treasury Securities [Member]
Securities available for sale
Investment securities available for sale	7,498	7,499
Fair Value Inputs Level 1 [Member] | Us Government Agencies Debt Securities Noncallable [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 1 [Member] | Us Government Agencies Debt Securities Callable [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 1 [Member] | US States And Political Subdivisions Member [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 1 [Member] | Private Label Mbs [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Purchase
Derivatives, included in assets:
Derivatives, included in assets	0	0
Fair Value Inputs Level 1 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Derivatives, included in liabilities	0	0
Fair Value Inputs Level 1 [Member] | Interest Rate Swap [Member]
Derivatives, included in assets:
Derivatives, included in assets	0	0
Derivatives, included in liabilities:
Derivatives, included in liabilities	0	0
Fair Value Inputs Level 2 [Member] | Forward Contracts [Member]
Derivatives, included in assets:
Derivatives, included in assets	17	174
Derivatives, included in liabilities:
Derivatives, included in liabilities	16	0
Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 2 [Member] | U S Treasury Securities [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 2 [Member] | Us Government Agencies Debt Securities Noncallable [Member]
Securities available for sale
Investment securities available for sale	220,856	200,903
Fair Value Inputs Level 2 [Member] | Us Government Agencies Debt Securities Callable [Member]
Securities available for sale
Investment securities available for sale	1,666,264	1,677,651
Fair Value Inputs Level 2 [Member] | US States And Political Subdivisions Member [Member]
Securities available for sale
Investment securities available for sale	43,623	48,904
Fair Value Inputs Level 2 [Member] | Private Label Mbs [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Purchase
Derivatives, included in assets:
Derivatives, included in assets	18	58
Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Derivatives, included in liabilities	18	58
Fair Value Inputs Level 2 [Member] | Interest Rate Swap [Member]
Derivatives, included in assets:
Derivatives, included in assets	67	162
Derivatives, included in liabilities:
Derivatives, included in liabilities	2,877	3,965
Fair Value Inputs Level 3 [Member] | Forward Contracts [Member]
Derivatives, included in assets:
Derivatives, included in assets	0	0
Derivatives, included in liabilities:
Derivatives, included in liabilities	0	0
Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 3 [Member] | U S Treasury Securities [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 3 [Member] | Us Government Agencies Debt Securities Noncallable [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 3 [Member] | Us Government Agencies Debt Securities Callable [Member]
Securities available for sale
Investment securities available for sale	0	0
Fair Value Inputs Level 3 [Member] | US States And Political Subdivisions Member [Member]
Securities available for sale
Investment securities available for sale	2,766	2,426
Fair Value Inputs Level 3 [Member] | Private Label Mbs [Member]
Securities available for sale
Investment securities available for sale	36,116	40,866
Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Purchase
Derivatives, included in assets:
Derivatives, included in assets	0	0
Fair Value Inputs Level 3 [Member] | Interest Rate Cap [Member] | Written
Derivatives, included in liabilities:
Derivatives, included in liabilities	0	0
Fair Value Inputs Level 3 [Member] | Interest Rate Swap [Member]
Derivatives, included in assets:
Derivatives, included in assets	0	0
Derivatives, included in liabilities:
Derivatives, included in liabilities	$ 0	$ 0