FAIR VALUE (Carrying Amounts and Fair Values of Company's Financial Instruments) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial Assets
Investments held-to-maturity and other equity securities	$ 46,094	$ 249,601
Loans, net of allowance	3,883,741	3,454,475
Other assets	93,328	90,866
Financial Liabilities
Time Deposits	586,039	508,444
Securities sold under retail repurchase agreements and federal funds purchased	125,119	109,145
Advances from FHLB	790,000	685,000
Subordinated debentures	30,000	35,000
Estimate of Fair Value Measurement [Member]
Financial Assets
Investments held-to-maturity and other equity securities	46,094	253,040
Loans, net of allowance	3,933,700	3,526,807
Other assets	93,328	90,866
Financial Liabilities
Time Deposits	584,868	508,000
Securities sold under retail repurchase agreements and federal funds purchased	125,119	109,145
Advances from FHLB	800,756	704,410
Subordinated debentures	29,985	14,694
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets
Investments held-to-maturity and other equity securities	0	0
Loans, net of allowance	0	0
Other assets	0	0
Financial Liabilities
Time Deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0	0
Subordinated debentures	0	0
Significant Other Observable Inputs (Level 2)
Financial Assets
Investments held-to-maturity and other equity securities	46,094	253,040
Loans, net of allowance	0	0
Other assets	93,328	90,866
Financial Liabilities
Time Deposits	584,868	508,000
Securities sold under retail repurchase agreements and federal funds purchased	125,119	109,145
Advances from FHLB	800,756	704,410
Subordinated debentures	0	0
Significant Unobservable Inputs (Level 3)
Financial Assets
Investments held-to-maturity and other equity securities	0	0
Loans, net of allowance	3,933,700	3,526,807
Other assets	0	0
Financial Liabilities
Time Deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0	0
Subordinated debentures	$ 29,985	$ 14,694