Nature of Business and Significant Accounting Policies - Allowance From Doubtful Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable:
Threshold period for considering receivable as past due	90 days
Changes in the allowance for doubtful accounts
Beginning of Year	$ 1,512,000	$ 1,073,000	$ 651,000
Additions	399,000	920,000	462,000
Write-offs	201,000	482,000	45,000
Recoveries	1,000	1,000	5,000
End of Year	1,711,000	1,512,000	1,073,000
Programming rights:
Impairment of programming rights	0	0	0
Amortization of programming rights	12,182,000	11,703,000	$ 10,370,000
Accumulated amortization of programming rights	$ 18,300,000	$ 19,700,000