PENDING BUSINESS COMBINATION Pending Business Combination - Pro Forma Information - (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information [Abstract]
Net interest income	$ 70,479,000	$ 68,818,000	$ 204,518	$ 207,931,000	$ 202,505,000	$ 387,725
Provision for loan and lease losses	4,462,000	1,886,000	834	7,451,000	7,381,000	10,140
Income before income taxes	36,025,000	32,975,000	92,591	104,860,000	96,543,000	170,132
Net Income			65,884			119,661
Business Acquisition, Pro Forma Balance Sheet Information [Abstract]
Loans and Leases Receivable, Net Amount	5,922,503,000		8,818,392	5,922,503,000		5,699,521,000
Assets	8,761,689,000		13,806,092	8,761,689,000		8,437,967,000
Deposits	6,726,090,000		9,987,298	6,726,090,000		6,525,788,000
Total shareholders' equity	$ 914,954,000	$ 861,137,000	$ 1,913,682	$ 914,954,000	$ 861,137,000	$ 865,224,000	$ 809,376,000