FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ 12,703	$ 12,587
Financial assets
Investment securities held-to-maturity	696,269	763,254
Other investments	53,285	51,077
FDIC indemnification asset	9,600	12,000
Deposits
Noninterest-bearing	1,476,563	1,547,985
Savings	2,398,262	2,142,189
Time	1,097,911	1,321,843
Carrying value
Financial assets
Cash and short-term investments	147,317	204,048
Investment securities held-to-maturity	696,269	763,254
Other investments	53,285	51,077
Loans held for sale	11,939	13,135
Loans and leases, net of ALLL	5,818,892	5,699,521
FDIC indemnification asset	9,599	12,017
Interest Receivable	19,968	18,503
Deposits
Noninterest-bearing	1,476,563	1,547,985
Interest-bearing demand	1,496,173	1,513,771
Savings	2,398,262	2,142,189
Time	1,097,911	1,321,843
Total deposits	6,468,909	6,525,788
Short-term borrowings	1,088,333	807,912
Long-term debt	119,669	119,589
Interest Payable	5,197	5,049
Fair value
Financial assets
Cash and short-term investments	147,317	204,048
Investment securities held-to-maturity	698,722	763,575
Loans held for sale	11,939	13,135
Loans and leases, net of ALLL	5,858,101	5,754,845
FDIC indemnification asset	5,378	6,720
Interest Receivable	19,968	18,503
Deposits
Noninterest-bearing	1,476,563	1,547,985
Interest-bearing demand	1,496,173	1,513,771
Savings	2,398,262	2,142,189
Time	1,092,974	1,316,333
Total deposits	6,463,972	6,520,278
Short-term borrowings	1,088,333	807,912
Long-term debt	119,101	117,878
Interest Payable	5,197	5,049
Fair Value, Inputs, Level 1 [Member] | Fair value
Financial assets
Cash and short-term investments	147,317	204,048
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases, net of ALLL	0	0
FDIC indemnification asset	0	0
Interest Receivable	0	0
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total deposits	0	0
Short-term borrowings	1,088,333	807,912
Long-term debt	0	0
Interest Payable	844	410
Fair Value, Inputs, Level 2 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	698,722	763,575
Loans held for sale	11,939	13,135
Loans and leases, net of ALLL	0	0
FDIC indemnification asset	0	0
Interest Receivable	7,126	5,705
Deposits
Noninterest-bearing	1,476,563	1,547,985
Interest-bearing demand	1,496,173	1,513,771
Savings	2,398,262	2,142,189
Time	1,092,974	1,316,333
Total deposits	6,463,972	6,520,278
Short-term borrowings	0	0
Long-term debt	119,101	117,878
Interest Payable	4,353	4,639
Fair Value, Inputs, Level 3 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases, net of ALLL	5,858,101	5,754,845
FDIC indemnification asset	5,378	6,720
Interest Receivable	12,842	12,798
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Interest Payable	$ 0	$ 0