INVESTMENTS IN DEBT AND EQUITY SECURITIES - (Securities Held to Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, Within One Year, Net Carrying Amount	$ 561	$ 561
Held-to-maturity Securities, Debt Maturities, After One Through Five Years, Net Carrying Amount	103,884	105,995
Held-to-maturity Securities, Debt Maturities, After Five Through Ten Years, Net Carrying Amount	60,590	61,726
Held-to-maturity Securities, Debt Maturities, After Ten Years, Net Carrying Amount	430,300	449,866
Held-to-maturity Securities, Amortized Cost	595,335	618,148
Held-to-maturity Securities, Gross Unrealized Gains	4,078	1,974
Held-to-maturity Securities, Gross Unrealized Losses	(2,072)	(5,850)
Held-to-maturity Securities, Fair Value	597,341	614,272
Held-to-maturity Securities Weighted Average Yield	1.88%	1.85%
Held-to-maturity Securities Weighted Average Yield With In One Year	3.07%	3.07%
Held-to-maturity Securities Weighted Average Yield After One Through Five Years	1.93%	1.88%
Held-to-maturity Securities Weighted Average Yield After Five Through Ten Years	1.25%	1.13%
Held-to-maturity Securities Weighted Average Yield After Ten Years	1.95%	1.94%
U.S. Government sponsored agencies [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, Within One Year, Net Carrying Amount	0	0
Held-to-maturity Securities, Debt Maturities, After One Through Five Years, Net Carrying Amount	0	0
Held-to-maturity Securities, Debt Maturities, After Five Through Ten Years, Net Carrying Amount	10,001	10,725
Held-to-maturity Securities, Debt Maturities, After Ten Years, Net Carrying Amount	0	0
Held-to-maturity Securities, Amortized Cost	10,001	10,725
Held-to-maturity Securities, Gross Unrealized Gains	64	42
Held-to-maturity Securities, Gross Unrealized Losses	0	0
Held-to-maturity Securities, Fair Value	10,065	10,767
Held-to-maturity Securities Weighted Average Yield	1.29%	1.25%
Residential mortgage-backed [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, Within One Year, Net Carrying Amount	0	0
Held-to-maturity Securities, Debt Maturities, After One Through Five Years, Net Carrying Amount	103,224	105,660
Held-to-maturity Securities, Debt Maturities, After Five Through Ten Years, Net Carrying Amount	48,400	50,512
Held-to-maturity Securities, Debt Maturities, After Ten Years, Net Carrying Amount	429,339	448,905
Held-to-maturity Securities, Amortized Cost	580,963	605,077
Held-to-maturity Securities, Gross Unrealized Gains	4,013	1,931
Held-to-maturity Securities, Gross Unrealized Losses	(1,984)	(5,782)
Held-to-maturity Securities, Fair Value	582,992	601,226
Held-to-maturity Securities Weighted Average Yield	1.89%	1.86%
State and political subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, Within One Year, Net Carrying Amount	561	561
Held-to-maturity Securities, Debt Maturities, After One Through Five Years, Net Carrying Amount	660	335
Held-to-maturity Securities, Debt Maturities, After Five Through Ten Years, Net Carrying Amount	2,189	489
Held-to-maturity Securities, Debt Maturities, After Ten Years, Net Carrying Amount	961	961
Held-to-maturity Securities, Amortized Cost	4,371	2,346
Held-to-maturity Securities, Gross Unrealized Gains	1	1
Held-to-maturity Securities, Gross Unrealized Losses	(88)	(68)
Held-to-maturity Securities, Fair Value	4,284	2,279
Held-to-maturity Securities Weighted Average Yield	1.78%	1.68%
Debt securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, Within One Year, Fair Value	561	561
Held-to-maturity Securities, Debt Maturities, After One Through Five Years, Fair Value	104,797	106,147
Held-to-maturity Securities, Debt Maturities, After Five Through Ten Years, Fair Value	61,100	62,000
Held-to-maturity Securities, Debt Maturities, After Ten Years, Fair Value	$ 430,883	$ 445,564