Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 22,991	$ 47,924
Short-term investments	30,000
Trade receivables, net of allowance for doubtful accounts of $2,989 and $3,040 (including related parties of $10,208 and $5,534)	60,709	66,399
Prepaid expenses and other current assets (including related parties of $274 and $274)	6,000	5,705
Total current assets	119,700	120,028
Property and equipment, net of accumulated depreciation of $201,240 and $198,282	56,963	57,874
Intangible assets subject to amortization, net of accumulated amortization of $79,117 and $78,234 (including related parties of $13,338 and $13,918)	15,774	16,656
Intangible assets not subject to amortization	220,701	220,701
Goodwill	50,081	50,081
Deferred income taxes	57,060	57,929
Other assets	1,611	1,693
Total assets	521,890	524,962
Current liabilities
Current maturities of long-term debt	3,750	3,750
Accounts payable and accrued expenses (including related parties of $4,017 and $3,909)	26,271	29,787
Total current liabilities	30,021	33,537
Long-term debt, less current maturities, net of unamortized debt issuance costs of $3,054 and $3,226	308,821	309,587
Other long-term liabilities	15,572	14,565
Total liabilities	$ 354,414	$ 357,689
Commitments and contingencies (note 4)
Stockholders' equity
Additional paid-in capital	$ 908,792	$ 910,228
Accumulated deficit	(736,579)	(738,849)
Accumulated other comprehensive income (loss)	(4,746)	(4,115)
Total stockholders' equity	167,476	167,273
Total liabilities and stockholders' equity	521,890	524,962
Class A common stock
Stockholders' equity
Common stock	6	6
Class B common stock
Stockholders' equity
Common stock	2	2
Class U common stock
Stockholders' equity
Common stock	$ 1	$ 1