EARNINGS PER SHARE - Computation of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
EARNINGS PER SHARE
Net income	$ 6,547	$ 9,443	$ 25,363	$ 27,455
Dividends paid on and earnings allocated to participating securities	(145)	(197)	(550)	(557)
Income attributable to common stock	$ 6,402	$ 9,246	$ 24,813	$ 26,898
Weighted average common shares outstanding, including participating securities	19,890	19,793	19,869	19,748
Weighted average participating securities (in shares)	(438)	(412)	(435)	(405)
Weighted average common shares outstanding	19,452	19,381	19,434	19,343
Basic earnings per common share (in dollars per share)	$ 0.33	$ 0.48	$ 1.28	$ 1.39
Income attributable to common stock	$ 6,402	$ 9,246	$ 24,813	$ 26,898
Impact of assumed conversions - interest on 8.5% trust preferred securities	0	0	0	32
Income attributable to common stock including assumed conversions	$ 6,402	$ 9,246	$ 24,813	$ 26,930
Weighted average common shares outstanding	19,452	19,381	19,434	19,343
Incremental shares from assumed conversions of options and restricted stock units	33	25	27	21
Incremental shares from assumed conversions of 8.5% trust preferred securities	0	0	0	23
Weighted average common and equivalent shares outstanding (in shares)	19,485	19,406	19,461	19,387
Diluted earnings per common share (in dollars per share)	$ 0.33	$ 0.48	$ 1.28	$ 1.39