SHAREHOLDERS' EQUITY (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 21, 2018	May 31, 2017	Feb. 26, 2016	Jan. 14, 2016	May 07, 2014	Jan. 11, 2010
Weighted average shares outstanding:
Weighted average basic common shares (in shares)	12,504,000	11,945,000	11,812,000
Effect of stock options (in shares)	1,043,000	1,626,000	886,000
Effect of dilutive share awards (in shares)	153,000	111,000	75,000
Effect of Convertible Senior Notes and warrants	397,000	0	0
Weighted average diluted common shares (in shares)	14,097,000	13,682,000	12,773,000
Additional disclosure
Interest rate	0.625%				0.625%
Common Stock Repurchases
Value of common stock authorized to be repurchased				$ 100,000,000.0		$ 40,000,000.0	$ 50,000,000.0	$ 10,000,000.0	$ 10,000,000
Purchase of treasury stock (in shares)	379,449	75,393	690,218
Value of treasury stock acquired	$ 92,606,000	$ 21,000,000	$ 48,524,000
Remaining authorized repurchase amount	$ 35,100,000
Employee Stock Option [Member]
Additional disclosure
Anti-dilutive securities excluded from calculation of diluted earnings per share	400,000	100,000