ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Non Covered Loans	Dec. 31, 2013 Non Covered Loans	Sep. 30, 2014 Commercial	Dec. 31, 2013 Commercial	Dec. 31, 2012 Commercial	Sep. 30, 2014 Commercial Non Covered Loans	Dec. 31, 2013 Commercial Non Covered Loans	Sep. 30, 2014 Real estate-construction	Dec. 31, 2013 Real estate-construction	Dec. 31, 2012 Real estate-construction	Sep. 30, 2014 Real estate-construction Non Covered Loans	Dec. 31, 2013 Real estate-construction Non Covered Loans	Sep. 30, 2014 Real estate-commercial	Dec. 31, 2013 Real estate-commercial	Dec. 31, 2012 Real estate-commercial	Sep. 30, 2014 Real estate-commercial Non Covered Loans	Dec. 31, 2013 Real estate-commercial Non Covered Loans	Sep. 30, 2014 Real estate - residential	Dec. 31, 2013 Real estate - residential	Dec. 31, 2012 Real estate - residential	Sep. 30, 2014 Real estate - residential Non Covered Loans	Dec. 31, 2013 Real estate - residential Non Covered Loans	Sep. 30, 2014 Installment	Dec. 31, 2013 Installment	Dec. 31, 2012 Installment	Sep. 30, 2014 Installment Non Covered Loans	Dec. 31, 2013 Installment Non Covered Loans	Sep. 30, 2014 Home equity	Dec. 31, 2013 Home equity	Dec. 31, 2012 Home equity	Sep. 30, 2014 Home equity Non Covered Loans	Dec. 31, 2013 Home equity Non Covered Loans	Sep. 30, 2014 All other	Dec. 31, 2013 All other	Dec. 31, 2012 All other	Sep. 30, 2014 All other Non Covered Loans	Dec. 31, 2013 All other Non Covered Loans
Allowance for loan and lease losses:
Balance at beginning of period	$ 42,027	$ 47,047	$ 43,829	$ 47,777		$ 43,829	$ 47,777	$ 10,568		$ 7,926	$ 10,568		$ 824		$ 3,268	$ 824		$ 20,478		$ 24,151	$ 20,478		$ 3,379		$ 3,599	$ 3,379		$ 365		$ 522	$ 365		$ 5,209		$ 5,173	$ 5,209		$ 3,006		$ 3,138	$ 3,006
Provision for loan and lease losses	1,093	1,413	2,281	6,863		2,281	8,714				517	5,385				274	(3,115)				855	2,659				61	593				(153)	(132)				721	1,937				6	1,387
Gross charge-offs	1,816	5,111	6,427	12,515		6,427	17,283				1,310	3,415				0	1				1,944	8,326				701	1,016				205	335				1,396	2,409				871	1,781
Recoveries	1,150	2,165	2,771	3,389		2,771	4,621				1,185	672				0	672				771	1,994				161	203				173	310				186	508				295	262
Total net charge-offs			3,656				12,662	125				2,743	0				(671)	1,173				6,332	540				813	32				25	1,210				1,901	576				1,519
Balance at end of period	42,454	45,514	42,454	45,514			43,829	10,960		7,926		10,568	1,098		3,268		824	20,160		24,151		20,478	2,900		3,599		3,379	180		522		365	4,720		5,173		5,209	2,436		3,138		3,006
Ending allowance on loans individually evaluated for impairment	4,510		4,510		5,302	4,510	5,302	802	2,080		802	2,080	0	0		0	0	3,338	2,872		3,338	2,872	368	348		368	348	0	0		0	0				2	2	0	0		0	0
Ending allowance on loans collectively evaluated for impairment						37,944	38,527				10,158	8,488				1,098	824				16,822	17,606				2,532	3,031				180	365				4,718	5,207				2,436	3,006
Loans and Leases:
Ending balance of loans individually evaluated for impairment						32,609	32,677				7,913	10,391				0	0				20,763	18,023				3,215	3,493				104	122				614	648				0	0
Ending balance of loans collectively evaluated for impairment						4,417,363	3,472,964				1,296,869	1,025,277				193,776	80,741				1,931,292	1,478,964				423,343	349,438				47,457	47,011				415,485	375,806				109,141	115,727
Loans and Leases Receivable, Net of Deferred Income	$ 4,449,972		$ 4,449,972		$ 3,505,641			$ 1,304,782	$ 1,035,668		$ 1,304,782	$ 1,035,668	$ 193,776	$ 80,741		$ 193,776	$ 80,741	$ 1,952,055	$ 1,496,987		$ 1,952,055	$ 1,496,987	$ 426,558	$ 352,931		$ 426,558	$ 352,931	$ 47,561	$ 47,133		$ 47,561	$ 47,133	$ 416,099	$ 376,454		$ 416,099	$ 376,454	$ 109,141	$ 115,727		$ 109,141	$ 115,727