SHAREHOLDERS' EQUITY (Details) - USD ($)	1 Months Ended	12 Months Ended
	Nov. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2017	Feb. 26, 2016	Jan. 14, 2016	Nov. 12, 2015	May 07, 2014	Jan. 11, 2010
Weighted average shares outstanding:
Weighted average basic common shares (in shares)		11,945,000	11,812,000	11,516,000
Effect of stock options (in shares)		1,626,000	886,000	866,000
Effect of dilutive share awards (in shares)		111,000	75,000	159,000
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants		0	0	0
Weighted average diluted common shares (in shares)		13,682,000	12,773,000	12,541,000
Additional disclosure
Interest rate		0.625%			0.625%
Common Stock Repurchases
Value of common stock authorized to be repurchased						$ 40,000,000.0	$ 50,000,000.0		$ 10,000,000.0	$ 10,000,000
Purchase of treasury stock (in shares)		75,393	690,218	5,250
Value of treasury stock acquired		$ 21,000,000	$ 48,524,000	$ 218,000
Remaining authorized repurchase amount		$ 27,700,000
Common stock issuance price for equity offering								$ 115.00
Proceeds from equity offering, net of offering costs	$ 91,500,000			$ 91,462,000
Equity offering underwriting discounts	5,900,000
Equity offering expenses	$ 700,000
Common Stock
Common Stock Repurchases
Issuance of stock for equity offering (in shares)	852,500			853,000
Proceeds from equity offering, net of offering costs				$ 9,000
Employee Stock Option [Member]
Additional disclosure
Anti-dilutive securities excluded from calculation of diluted earnings per share		100,000