Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accounts payable	$ 23,700	$ 6,100
Accrued payroll and compensated absences	6,700	6,300
Accrued bonuses	5,600	1,400
Professional fees	300	500
Deferred revenue	3,000	3,200
Accrued national representation fees	800	1,100
Income taxes payable	600	400
Other taxes payable	3,100
Amounts due under joint sales agreements	1,000	2,900
Accrued property taxes	1,300	1,600
Accrued capital expenditures	1,700	1,000
Accrued media costs – digital	1,300	1,200
Accrued contingent consideration	2,300
Other	8,100	5,100
Accounts Payable and Accrued Expenses	$ 59,522	$ 30,810