SUBSEQUENT EVENT (Details) - USD ($)			2 Months Ended	12 Months Ended
	Feb. 22, 2019	Jan. 10, 2019	Feb. 28, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 20, 2019	Feb. 21, 2018	Feb. 26, 2016	Jan. 14, 2016	May 07, 2014	Jan. 11, 2010
Subsequent Event [Line Items]
Proceeds from revolving credit facility				$ 125,000,000	$ 0	$ 0
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
Subsequent Event [Member]
Subsequent Event [Line Items]
Value of common stock authorized to be repurchased							$ 150,000,000.0
Purchase of treasury stock (in shares)			17,501
Value of treasury stock acquired			$ 3,900,000
Remaining authorized repurchase amount			$ 181,200,000
Proceeds from sale of property held-for-sale	$ 24,750,000
Earnest money deposit	$ 1,000,000
ValuePenguin [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Acquisition purchase consideration		$ 105,000,000
Revolving Credit Facility [Member] | ValuePenguin [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from revolving credit facility		$ 90,000,000