BUSINESS COMBINATION BUSINESS COMBINATIONS (Details) - USD ($) $ in Thousands		6 Months Ended		12 Months Ended
	Apr. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Cash consideration		$ 43
Stock consideration		1,045,876
Warrant consideration		14,460
Options consideration		1,577
Total purchase consideration	$ 1,100,000	1,061,956
Cash		71,681
Investment securities available for sale		901,008
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Held to Maturity Securities		171,423
Other investments		28,763
Loans		2,791,954
Premises and equipment		99,098
Other real estate owned		1,361
Intangible assets		41,750
Other assets		155,945
Assets held for sale		127,775
Total assets acquired		4,390,758
Deposits		3,264,038
Subordinated notes		49,027
FHLB advances		291,887
Other borrowings		205,620
Other liabilities		21,449
Liabilities held for sale		175,722
Total liabilities assumed		4,007,743		$ 0
Net identifiable assets		383,015
Goodwill		$ 678,941	$ 0	$ 0