DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Notional amount	$ 5,425,405,000		$ 4,005,212,000
Additional amount in excess of posted collateral required in case of breached agreements	$ 900,000		1,100,000
Interest rate contracts [Member]
Derivative [Line Items]
Maximum length of time hedged in interest rate cash flow hedge	6 years
Period to reclassification of cash flow hedge gain loss	12 months
Derivative gains to be reclassified within twelve months	$ 385,000
Derivative gains to be reclassified within twelve months, net of tax	250,000
Derivative gain or loses excluded from assessment of hedge effectiveness	0
Hedge ineffectiveness	0	$ 0
Gains or losses from cash flow hedge derivatives reclassified to earnings	$ 0	$ 0
Interest Rate Lock Commitments [Member] | Minimum [Member]
Derivative [Line Items]
Lock in period for interest rates	30 days
Interest Rate Lock Commitments [Member] | Maximum [Member]
Derivative [Line Items]
Lock in period for interest rates	90 days
Credit Risk Contract Sold [Member]
Derivative [Line Items]
Notional amount	$ 159,700,000.0
Maximum exposure under credit risk agreement assuming customer default	$ 153,000		$ 123,000
Credit Risk Contract Sold [Member] | Minimum [Member]
Derivative [Line Items]
Risk participation agreements, term	2 months
Credit Risk Contract Sold [Member] | Maximum [Member]
Derivative [Line Items]
Risk participation agreements, term	9 years