SECURITIES (Narrative) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) security	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) security
Schedule of Investments [Line Items]
Net unrealized gains (losses) on available-for-sale securities, net of tax	$ (6,543)		$ (6,085)
Deferred tax assets, unrealized losses on available for sale securities	3,500		$ 3,300
Payments to acquire investments	$ 77,300	$ 70,800
AFS securities in unrealized loss positions, number of positions | security	232		209
AFS and HTM securities in Continues Unrealized Loss Position	$ 730,300		$ 658,500
AFS and HTM Securities Unrealized Loss Accumulated in Investments	13,800		13,200
Fair Value - 12 Months of More	98,729		$ 103,708
Unrealized Loss as a Percent of Fair Value			2.00%
Proceeds from Sale of Available-for-sale Securities	0
Investment securities sold, carrying amount		0
Federal Home Loan Bank Stock	20,000		$ 17,800
Federal Reserve Bank Stock	5,400		5,400
Security pledged as collateral, amortized cost	604,000		597,300
Security pledged as collateral, fair value	595,700		589,700
Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
AFS and HTM Securities Unrealized Loss Accumulated in Investments	4,200		3,900
Fair Value - 12 Months of More	98,700		103,700
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Schedule of Investments [Line Items]
Fair Value - 12 Months of More	28,177		29,496
Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
Fair Value - 12 Months of More	$ 70,552		$ 74,212
Available-for-sale Securities
Schedule of Investments [Line Items]
Payments to acquire investments		66,900
Held-to-maturity Securities
Schedule of Investments [Line Items]
Payments to acquire investments		$ 3,900