Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts receivable, allowance	$ 605	$ 388
Property and equipment, accumulated depreciation and amortization	83,645	73,068
Software development costs, accumulated amortization	3,072	1,791
Acquired intangible assets, accumulated amortization	$ 13,970	$ 10,173
Class A Common Stock
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	225,000,000	225,000,000
Common Stock, shares issued	55,144,066	53,763,871
Common Stock, shares outstanding	55,144,066	53,763,871
Class B Common Stock
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	75,000,000	75,000,000
Common Stock, shares issued	4,801,245	4,997,769
Common Stock, shares outstanding	4,801,245	4,997,769