Stockholders' Equity - Additional Information (Details)						1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 01, 2018 shares	Oct. 19, 2017 employee shares	Apr. 03, 2017 employee shares	Feb. 27, 2017 shares	Oct. 03, 2016 employee shares	Apr. 30, 2018	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($)	Dec. 31, 2017 $ / shares shares	Dec. 16, 2016 shares	Nov. 30, 2011 shares	Jun. 27, 2007 shares
Preferred Stock
Preferred stock, par value (in dollars per share) | $ / shares							$ 0.001		$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)							5,000,000		5,000,000		5,000,000
Preferred stock, shares issued (in shares)							0		0		0
Preferred stock, shares outstanding (in shares)							0		0		0
Common Stock
Common stock, par value (in dollars per share) | $ / shares							$ 0.001		$ 0.001		$ 0.001
Common stock, shares authorized (in shares)							100,000,000		100,000,000		100,000,000
Issuance of common stock for vested RSAs (in shares)									1,075,893		1,013,763
Exercise of stock options (in shares)									131,051		2,080,648
Warrants exercised (in shares)									0		675,000
Stock-Based Compensation
Stock-based compensation expense | $							$ 2,090,870	$ 2,368,192	$ 4,259,795	$ 3,502,350
Unvested restricted stock awards
Stock-Based Compensation
Vesting period									3 years
Partial vesting period									1 year
Unrecognized compensation cost, period of recognition									2 years 2 months 12 days
Unrecognized compensation cost, RSAs | $							11,200,000		$ 11,200,000
Unvested restricted stock awards | Tranche 1
Stock-Based Compensation
Vesting percentage									33.00%
Unvested restricted stock awards | Tranche 2
Stock-Based Compensation
Vesting percentage									33.00%
Unvested restricted stock awards | Tranche 3
Stock-Based Compensation
Vesting percentage									33.00%
Performance Shares
Stock-Based Compensation
Unrecognized compensation cost, period of recognition									2 years 9 months 18 days
Unrecognized compensation cost, RSAs | $							1,700,000		$ 1,700,000
Stock options
Stock-Based Compensation
Unrecognized compensation cost, stock options | $							2,800,000		$ 2,800,000
Unrecognized compensation cost, period of recognition									1 year 8 months 12 days
2012 Omnibus Incentive Plan
Common Stock
Exercise of stock options (in shares)									131,051
Stock-Based Compensation
Shares reserved for issuance (in shares)	300,924											10,500,000
Intrinsic value of options exercised | $									$ 200,000	200,000
Stock-based compensation expense | $							400,000	700,000	$ 800,000	1,100,000
Options granted (in shares)									0
2012 Omnibus Incentive Plan | Unvested restricted stock awards
Stock-Based Compensation
Vesting period									3 years
Stock-based compensation expense | $							1,100,000	1,000,000	$ 2,200,000	1,600,000
Shares granted (in shares)									449,500
Expiration period									3 years
2012 Omnibus Incentive Plan | Performance Shares
Stock-Based Compensation
Vesting period						3 years
Stock-based compensation expense | $							100,000		$ 100,000
Shares granted (in shares)									615,500
Fair value of PSUs at date of grant | $							$ 1,800,000		$ 1,800,000
2018 Omnibus Incentive Plan
Stock-Based Compensation
Shares reserved for issuance (in shares)												8,800,924
Shares available for grant (in shares)							7,100,000		7,100,000
Fungible ratio	1.4
2018 Omnibus Incentive Plan | Unvested restricted stock awards
Stock-Based Compensation
Vesting period									3 years
Stock-based compensation expense | $							$ 100,000		$ 100,000
Shares granted (in shares)									1,522,034
Expiration period									3 years
Amended and Restated 2006 Stock Incentive Plan
Stock-Based Compensation
Shares reserved for issuance (in shares)												2,100,000
2006 Stock Plan
Common Stock
Exercise of stock options (in shares)									0
Stock-Based Compensation
Shares reserved for issuance (in shares)														3,700,000
Intrinsic value of options exercised | $									$ 0	6,300,000
Options granted (in shares)									0
The Amended and Restated 2016 Inducement Omnibus Incentive Plan
Common Stock
Exercise of stock options (in shares)									0
Stock-Based Compensation
Stock-based compensation expense | $							100,000	200,000	$ 200,000	400,000
Options granted (in shares)									0
Additional shares authorized for issuance (in shares)				2,000,000
The Amended and Restated 2016 Inducement Omnibus Incentive Plan | Former Skout Employees
Stock-Based Compensation
Options granted (in shares)					355,000
The Amended and Restated 2016 Inducement Omnibus Incentive Plan | Unvested restricted stock awards
Stock-Based Compensation
Vesting period									3 years
Stock-based compensation expense | $							$ 300,000	$ 400,000	$ 700,000	$ 500,000
Shares granted (in shares)									0
Expiration period									3 years
Skout
Stock-Based Compensation
Number of former employees of acquiree | employee					25
If(we), Inc. | Unvested restricted stock awards
Stock-Based Compensation
Number of former employees of acquiree | employee			83
Restricted stock awards granted (in shares)			717,500
If(we), Inc. | Stock options
Stock-Based Compensation
Options granted (in shares)			75,000
Lovoo, Inc. | Unvested restricted stock awards
Stock-Based Compensation
Number of former employees of acquiree | employee		96
Restricted stock awards granted (in shares)		531,500
Series A-1 Preferred Stock
Preferred Stock
Preferred stock, shares authorized (in shares)													5,000,000
Preferred stock, shares issued (in shares)							0		0		0
Preferred stock, shares outstanding (in shares)							0		0		0
Minimum | 2012 Omnibus Incentive Plan | Performance Shares
Stock-Based Compensation
Payout threshold range									0.00%
Maximum | 2012 Omnibus Incentive Plan | Performance Shares
Stock-Based Compensation
Payout threshold range									170.00%