CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
REVENUE	$ 545,451	$ 462,609	$ 403,083
COSTS AND EXPENSES:
Cost of revenue	256,994	224,581	199,053
Marketing	152,387	124,209	107,706
General and administrative	68,290	64,651	59,231
Depreciation and amortization	13,736	9,158	7,849
Total costs and expenses	491,407	422,599	373,839
Operating income	54,044	40,010	29,244
INTEREST EXPENSE, net	26	169	142
Income before income tax expense	54,018	39,841	29,102
INCOME TAX EXPENSE	18,549	13,698	9,791
Net income	$ 35,469	$ 26,143	$ 19,311
BASIC INCOME PER COMMON SHARE	$ 1.20	$ 0.90	$ 0.67
DILUTED INCOME PER COMMON SHARE	$ 1.19	$ 0.89	$ 0.66
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic	29,213	28,695	28,323
Diluted	29,545	29,175	28,787
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.70	$ 0.70	$ 0.70