Stockholders' Equity - Capitalization (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	Jun. 20, 2017 USD ($) $ / shares	Oct. 21, 2016 shares	Jun. 08, 2016 USD ($) $ / shares shares	Mar. 16, 2016 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) D $ / shares shares	Dec. 31, 2016 USD ($)	Apr. 04, 2013 item
Capitalization
Amount of stock repurchased | $					$ 21,910	$ 30,735
Period before April 4, 2018
Capitalization
Number of trading days | D					20
Number of consecutive trading days | D					30
Common Class B
Capitalization
Common stock shares issued, including forfeiture					20,800,998
Common stock shares outstanding, including forfeiture					20,800,998
Number of votes per share of common stock | item							10
Common Class B | Period before April 4, 2018
Capitalization
Number of shares forfeited					1,100,000
Common Class A
Capitalization
Common stock shares issued, including forfeiture					20,285,427
Common stock shares outstanding, including forfeiture					20,285,427
Number of shares repurchased			2,800,000	100,000	1,800,000
Stock repurchase price (in dollars per share) | $ / shares	$ 0.0001		$ 10.50	$ 13.35
Amount of stock repurchased | $			$ 29,400	$ 1,300
Number of votes per share of common stock | item							1
Remaining authorization for future repurchases | $					$ 3,100
Common Class A | Treasury Stock
Capitalization
Number of shares repurchased					1,800,000
Amount of stock repurchased | $					$ 21,910	$ 30,735
Common Class A | Maximum
Capitalization
Amount of stock repurchased | $	$ 25,000
Common Class A | Period before April 4, 2018
Capitalization
Number of shares forfeited					900,000
Stock trigger price (in dollars per share) | $ / shares					$ 15.00
IinterMedia Partners | Common Class B
Capitalization
Number of shares forfeited		419,383
IinterMedia Partners | Common Class A
Capitalization
Common stock Class B shares transferred		9,200,000