FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ 10,750	$ 14,431
Financial assets
Investment securities held-to-maturity	900,521	837,272
Other investments	49,986	47,427
Covered loans	320,730	438,972
FDIC indemnification asset	24,160	45,091
Deposits
Noninterest-bearing	1,243,367	1,147,452
Savings	1,827,590	1,612,005
Time	1,247,334	952,327
Carrying value
Financial assets
Cash and short-term investments	143,725	143,450
Investment securities held-to-maturity	900,521	837,272
Other investments	49,986	47,427
Loans held for sale	16,816	8,114
Loans - excluding covered loans	4,407,518	3,461,812
Covered loans	320,730	438,972
FDIC indemnification asset	24,160	45,091
Deposits
Noninterest-bearing	1,243,367	1,147,452
Interest-bearing demand	1,214,726	1,125,723
Savings	1,827,590	1,612,005
Time	1,247,334	952,327
Total deposits	5,533,017	4,837,507
Short-term borrowings	919,303	748,749
Long-term debt	52,656	60,780
Fair value
Financial assets
Cash and short-term investments	143,725	143,450
Investment securities held-to-maturity	901,659	824,985
Other investments	49,986	47,427
Loans held for sale	16,816	8,114
Loans - excluding covered loans	4,416,740	3,455,776
Covered loans	318,372	451,545
FDIC indemnification asset	12,482	34,820
Deposits
Noninterest-bearing	1,243,367	1,147,452
Interest-bearing demand	1,214,726	1,125,723
Savings	1,827,590	1,612,005
Time	1,244,218	951,220
Total deposits	5,529,901	4,836,400
Short-term borrowings	919,303	748,749
Long-term debt	54,385	62,706
Fair Value, Inputs, Level 1 [Member] | Fair value
Financial assets
Cash and short-term investments	143,725	143,450
Investment securities held-to-maturity	0	0
Other investments	0	0
Loans held for sale	0	0
Loans - excluding covered loans	0	0
Covered loans	0	0
FDIC indemnification asset	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	919,303	748,749
Long-term debt	0	0
Fair Value, Inputs, Level 2 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	901,659	824,985
Other investments	49,986	47,427
Loans held for sale	16,816	8,114
Loans - excluding covered loans	0	0
Covered loans	0	0
FDIC indemnification asset	0	0
Deposits
Noninterest-bearing	1,243,367	1,147,452
Interest-bearing demand	1,214,726	1,125,723
Savings	1,827,590	1,612,005
Time	1,244,218	951,220
Total deposits	5,529,901	4,836,400
Short-term borrowings	0	0
Long-term debt	54,385	62,706
Fair Value, Inputs, Level 3 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	0	0
Other investments	0	0
Loans held for sale	0	0
Loans - excluding covered loans	4,416,740	3,455,776
Covered loans	318,372	451,545
FDIC indemnification asset	12,482	34,820
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