PARENT COMPANY FINANCIAL INFORMATION - INCOME STATEMENT (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income
Total interest income	$ 58,022	$ 57,152	$ 56,797	$ 57,194	$ 50,104	$ 46,473	$ 46,009	$ 44,888	$ 229,165	$ 187,474	$ 168,913
Expense
Interest expense	15,612	14,742	13,686	13,061	11,798	11,513	10,585	9,608	57,101	43,504	29,348
Income tax benefit	(2,521)	(2,192)	(3,360)	(2,090)	(5,870)	(3,890)	(3,353)	(3,008)	(10,163)	(16,121)	(10,325)
Net income	$ 17,381	$ 20,303	$ 20,203	$ 16,251	$ 10,331	$ 14,511	$ 14,481	$ 14,989	74,138	54,312	49,349
Parent
Income
Dividends from subsidiary									90,000	27,000	30,000
Interest income									78	60	51
Total interest income									90,078	27,060	30,051
Expense
Interest expense									8,269	7,646	3,334
Other									3,662	5,869	3,227
Total expense									11,931	13,515	6,561
Income before income tax expense									78,147	13,545	23,490
Income tax benefit									2,489	4,242	2,278
Income before equity in undistributed earnings of subsidiaries									80,636	17,787	25,768
Equity in undistributed earnings of subsidiaries									(6,498)	36,525	23,581
Net income									$ 74,138	$ 54,312	$ 49,349