CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
REVENUE	$ 158,149	$ 124,571	$ 565,720	$ 436,504
COSTS AND EXPENSES:
Cost of revenue	72,357	57,694	259,684	205,394
Marketing	42,067	33,499	168,585	128,441
General and administrative	18,626	16,707	59,620	51,744
Depreciation and amortization	3,755	4,332	11,321	10,160
Total costs and expenses	136,805	112,232	499,210	395,739
Operating income	21,344	12,339	66,510	40,765
INTEREST (INCOME) EXPENSE, net	(48)	(11)	(74)	23
Income before income tax expense	21,392	12,350	66,584	40,742
INCOME TAX EXPENSE	6,365	4,401	19,638	14,123
Net income	$ 15,027	$ 7,949	$ 46,946	$ 26,619
BASIC INCOME PER COMMON SHARE	$ 0.50	$ 0.27	$ 1.57	$ 0.90
DILUTED INCOME PER COMMON SHARE	$ 0.49	$ 0.27	$ 1.54	$ 0.90
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic	29,799	29,320	29,685	29,162
Diluted	30,299	29,613	30,164	29,465
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.175	$ 0.175	$ 0.525	$ 0.525