INCOME TAXES - (Summary of Provision for Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)						$ 2,431	$ 5,076	$ 15,523
Deferred Federal Income Tax Expense (Benefit)						810	(4,714)	5,515
Federal income tax expense						3,241	362	21,038
State and Local Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current						494	674	2,489
Deferred						(150)	(494)	562
State income tax expense						344	180	3,051
Total income tax expense	$ (3,781)	$ 1,988	$ 1,435	$ 3,423	$ (358)	$ 3,585	$ 542	$ 24,089