STOCKHOLDERS' EQUITY (Narrative) (Details) - USD ($)			3 Months Ended												12 Months Ended
	Feb. 28, 2018	Oct. 25, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 03, 2016
Stockholders Equity Description [Line Items]
Exercise of stock options															$ 4,266,000	$ 2,760,000	$ 3,182,000
Employee tax withholdings related to the vesting of equity awards															4,545,000	$ 2,657,000	$ 2,610,000
Purchase and retirement of common stock, value															$ 2,285,000
Dividend paid per share to all stockholders of record (in Dollars per Share)			$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175
Purchased and placed in treasury, shares															72,000
Purchase and placed in treasury, value															$ 3,485,000
Preferred stock, shares authorized (in Shares)			5,000,000				5,000,000								5,000,000	5,000,000
Dividend Declared [Member] | Subsequent Event [Member]
Stockholders Equity Description [Line Items]
Dividends payable (in Description)	Quarterly
Dividends payable, amount per share (in Dollars per Share)	$ 0.25
Dividends payable, date to be paid (Date)	Mar. 19, 2018
Dividends payable, date of record (Date)	Mar. 08, 2018
Stock Option [Member]
Stockholders Equity Description [Line Items]
Exercise of stock options (in Shares)															271,000	286,000	335,000
Common Stock [Member]
Stockholders Equity Description [Line Items]
Exercise of stock options (in Shares)															271,000	286,000	335,000
Common stock surrendered by employees in satisfaction of minimum tax withholding associated with equity award vesting (in Shares)															90,000	128,000	140,000
Employee tax withholdings related to the vesting of equity awards															$ 4,545,000	$ 2,657,000	$ 2,610,000
Purchase and retirement of common stock, shares															51,000
Purchase and retirement of common stock, value															$ 0
Common stock issued for services (in Shares)															14,000	27,000	22,000
Share repurchase program commencement date		Nov. 04, 2017
Purchase and placed in treasury, value															$ 0
Common Stock [Member] | Maximum [Member]
Stockholders Equity Description [Line Items]
Common stock authorized to repurchase amount		$ 50,000,000																$ 50,000,000
Common Stock [Member] | Surrender of Shares by Employees for Tax Withholding Obligations [Member]
Stockholders Equity Description [Line Items]
Purchase and retirement of common stock, shares															22,000
Purchase and retirement of common stock, value															$ 785,000
Common Stock [Member] | Open-market Transactions [Member]
Stockholders Equity Description [Line Items]
Purchase and retirement of common stock, shares															29,000
Purchase and retirement of common stock, value															$ 1,500,000
Common Stock [Member] | Stock Option [Member]
Stockholders Equity Description [Line Items]
Exercise of stock options (in Shares)															271,000	286,000	335,000