CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
REVENUE	$ 159,255	$ 158,149	$ 561,496	$ 565,720
COSTS AND EXPENSES:
Cost of revenue	76,010	72,357	263,032	259,684
Marketing	43,018	42,067	176,167	168,585
Selling, general and administrative	16,024	18,626	54,607	59,620
Depreciation and amortization	3,931	3,755	11,531	11,321
Total costs and expenses	138,983	136,805	505,337	499,210
Operating income	20,272	21,344	56,159	66,510
INTEREST INCOME, net	(314)	(48)	(512)	(74)
Income before income tax expense	20,586	21,392	56,671	66,584
INCOME TAX EXPENSE	4,592	6,365	11,738	19,638
Net income	$ 15,994	$ 15,027	$ 44,933	$ 46,946
BASIC INCOME PER COMMON SHARE	$ 0.54	$ 0.50	$ 1.51	$ 1.57
DILUTED INCOME PER COMMON SHARE	$ 0.54	$ 0.49	$ 1.50	$ 1.54
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic	29,208	29,799	29,466	29,685
Diluted	29,573	30,299	29,797	30,164
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.250	$ 0.175	$ 0.750	$ 0.525