Quarterly Results of Operations Data (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	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, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenues	$ 40,119,076	$ 32,246,472	$ 31,329,468	$ 20,058,797	$ 29,222,186	$ 17,191,261	$ 16,388,991	$ 13,321,671	$ 123,753,813	$ 76,124,109	$ 56,903,773
Operating costs and expenses:
Sales and marketing	6,050,466	4,600,148	4,599,842	5,105,508	6,313,958	3,228,262	3,226,344	2,321,423	20,355,964	15,089,987	6,618,837
Product development and content	19,698,097	16,021,977	16,526,905	8,457,494	8,059,563	5,808,449	6,214,062	5,708,100	60,704,473	25,790,173	24,615,304
General and administrative	6,504,840	5,021,739	5,160,799	2,862,427	3,063,319	2,215,727	1,867,590	2,348,168	19,549,805	9,494,804	14,534,861
Depreciation and amortization	3,954,243	2,969,570	2,965,175	1,684,839	1,802,568	761,460	753,918	751,264	11,573,827	4,069,211	3,140,205
Acquisition and restructuring	3,502,800	3,378,838	3,769,425	1,500,429	829,169	467,777	1,160,349	0	12,151,492	2,457,295	0
Goodwill impairment	56,428,861	0	0	0					56,428,861	0	0
Total operating costs and expenses	96,139,307	31,992,272	33,022,146	19,610,697	20,068,577	12,481,675	13,222,263	11,128,955	180,764,422	56,901,470	48,909,207
(Loss) income from operations	(56,020,231)	254,200	(1,692,678)	448,100	9,153,609	4,709,586	3,166,728	2,192,716	(57,010,609)	19,222,639	7,994,566
Other income (expense):
Interest income	387	1,374	1,400	2,570	2,488	7,135	6,447	5,115	5,731	21,185	21,037
Interest expense	(438,445)	(244,361)	(175,254)	(2,332)	(3,160)	(4,123)	(5,360)	(6,745)	(860,392)	(19,388)	(459,962)
Change in warrant liability					0	(318,983)	(787,391)	241,777	0	(864,596)	(616,607)
(Loss) gain on foreign currency adjustment	(30,416)	9,357	(9,229)	(2,200)	69	(1,206)	18,201	16,352	(32,488)	33,416	0
Other	9,631	0	0	0					9,631	0	0
Total other expense	(458,843)	(233,630)	(183,083)	(1,962)	(603)	(317,177)	(768,103)	256,499	(877,518)	(829,383)	(1,748,637)
(Loss) income before income tax (expense) benefit	(56,479,074)	20,570	(1,875,761)	446,138	9,153,006	4,392,409	2,398,625	2,449,215	(57,888,127)	18,393,256	6,245,929
Income tax (expense) benefit	(11,637,816)	2,202,152	2,732,356	(292)	749,916	0	27,219,764	(94,317)	(6,703,600)	27,875,362	(276,301)
Net (loss) income	$ (68,116,890)	$ 2,222,722	$ 856,595	$ 445,846	$ 9,902,922	$ 4,392,409	$ 29,618,389	$ 2,354,898	$ (64,591,727)	$ 46,268,618	$ 5,969,628
Basic and diluted net (loss) income per common stockholders:
Basic net (loss) income per common stockholders (in dollars per share)	$ (0.95)	$ 0.03	$ 0.01	$ 0.01	$ 0.17	$ 0.08	$ 0.61	$ 0.05	$ (0.94)	$ 0.89	$ 0.13
Diluted net (loss) income per common stockholders (in dollars per share)	$ (0.95)	$ 0.03	$ 0.01	$ 0.01	$ 0.15	$ 0.07	$ 0.55	$ 0.04	$ (0.94)	$ 0.80	$ 0.12
Weighted average shares outstanding:
Basic (in shares)	71,808,179	71,800,274	70,122,234	61,093,810	58,856,831	53,231,369	48,218,184	47,458,748	68,743,956	51,963,702	45,419,175
Diluted (in shares)	71,808,179	76,078,563	74,885,903	66,204,620	64,121,470	59,048,821	54,061,306	53,666,626	68,743,956	57,745,652	49,535,826