The Company and Significant Accounting Policies - Additional Information (Detail)					3 Months Ended						9 Months Ended		12 Months Ended	25 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 30, 2014 USD ($)	Nov. 25, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016 USD ($) shares	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($) shares	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($) shares	Jun. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) $ / shares shares	Aug. 18, 2014 USD ($)	Dec. 16, 2013 USD ($) Derivative	Aug. 02, 2013 USD ($)	May 31, 2013 USD ($)
Accounting Policies [Line Items]
Number of Class A common stock shares converted | shares											1
Share-based compensation expenses								$ 700,000		$ 900,000	$ 2,600,000	$ 2,700,000
Total unrecognized compensation expense employee stock option plans								$ 300,000			$ 300,000			$ 300,000
Shares of dilutive securities not included in computation of diluted income per share | shares								509		10,211	14,331	50,806
Amount approved under share purchase program			$ 20,000,000												$ 10,000,000
Additional share amount added to repurchase program			$ 10,000,000
Purchases of short-term investments											$ 30,000,000
Unamortized debt issuance costs	$ 3,226,000							$ 2,704,000			$ 2,704,000			2,704,000
Interest Rate Swap Agreements
Accounting Policies [Line Items]
Interest rate swap inception date											Dec. 16, 2013
Number of forward-starting swap agreements | Derivative																3
Aggregated notional amount of interest swap agreements																$ 186,000,000
Derivative average Interest rate																2.73%
Derivative fixed Interest rate																5.23%
Interest rate swap effective date											Dec. 31, 2015
Interest rate swap expiration date											Dec. 31, 2018
Change in fair value of interest rate gain (loss)								600,000		$ (1,100,000)	$ 100,000	$ (2,300,000)
Interest paid related to interest rate swap								800,000			2,500,000
Unrealized gains or losses included in accumulated other comprehensive income or loss											0
Fair value of the interest rate swap liability	6,600,000							$ 6,500,000			$ 6,500,000			$ 6,500,000
2013 Credit Facility
Accounting Policies [Line Items]
Effective interest rate								3.50%			3.50%			3.50%
Interest rate on borrowings under 2013 Credit Facility											if a Base Rate Loan, one and one half percent (1.50%) per annum and (B) if a LIBOR Rate Loan, two and one half percent (2.50%) per annum;
Percentage of repricing fee											1.00%
Certain customary events of default, number of business days to default in the payment of interest on borrowings											3 days
Certain customary events of default, number of days default continue for compliance with other agreement											30 days
Certain customary events of default, number of days default continue for financial statement delivery obligations											10 days
Certain customary events of default, indebtedness aggregate amount											$ 15,000,000
Certain customary events of default, failure in payment of final judgments aggregate amount											$ 15,000,000
Certain customary events of default, failure in payment of final judgments aggregate amount period											30 days
2013 Credit Facility | Base Rate Margin
Accounting Policies [Line Items]
Variable interest rate basis spread on debt											1.50%
2013 Credit Facility | LIBOR Margin
Accounting Policies [Line Items]
Variable interest rate basis spread on debt											2.50%
Term Loan B Facility
Accounting Policies [Line Items]
Gain (loss) on debt extinguishment											$ (29,700,000)
Repayment of loans	$ 20,000,000	$ 20,000,000		$ 10,000,000
Term Loan B Facility | 2013 Credit Facility
Accounting Policies [Line Items]
Senior Secured debt																		$ 375,000,000
Maturity date of revolving credit facility											May 31, 2020
Period considered for applicability of repricing fees											6 months
Principal amount repurchased																	$ 324,000,000
Redemption price on principal amount with net proceeds, accrued and unpaid expense																	106.563%
Carrying value of term loan								$ 311,000,000			$ 311,000,000			$ 311,000,000
Unamortized debt issuance costs								2,700,000			2,700,000			2,700,000
Estimated fair value of term loan								313,700,000			$ 313,700,000			313,700,000
Senior Secured Revolving Credit Facility | 2013 Credit Facility
Accounting Policies [Line Items]
Senior Secured debt																		30,000,000
Maturity date of revolving credit facility											May 31, 2018
Term Loan A | 2013 Credit Facility
Accounting Policies [Line Items]
Senior Secured debt																		20,000,000
Maturity date of revolving credit facility											Aug. 01, 2013
Term Loan And Revolving Credit Facility | 2013 Credit Facility
Accounting Policies [Line Items]
Additional borrowing capacity																		$ 100,000,000
Term Loan | 2013 Credit Facility
Accounting Policies [Line Items]
Interest rate on borrowings under 2013 Credit Facility											if a Base Rate Loan, one and one half percent (1.50%) per annum and (ii) if a LIBOR Rate Loan, two and one half percent (2.50%) per annum;
Term Loan | 2013 Credit Facility | Base Rate Margin
Accounting Policies [Line Items]
Variable interest rate basis spread on debt											1.50%
Term Loan | 2013 Credit Facility | LIBOR Margin
Accounting Policies [Line Items]
Variable interest rate basis spread on debt											2.50%
Chanclazo Studios, Inc
Accounting Policies [Line Items]
Cost method investments								$ 300,000			$ 300,000			$ 300,000
Cost method investment ownership percentage								3.00%			3.00%			3.00%
Investment milestone description											If certain quarterly performance targets are met by Chanclazo, the Company may purchase an additional 3% ownership interest in each of the next three quarters, resulting in a total potential interest of 12% for $1.0 million.
Option to invest additional fund in ownership interest, amount								$ 1,000,000			$ 1,000,000			$ 1,000,000
Option to invest additional fund in ownership interest, in percentage								12.00%			12.00%			12.00%
Chanclazo Studios, Inc | Scenario, Forecast
Accounting Policies [Line Items]
Cost method investments					$ 1,000,000								$ 1,000,000
Performance based additional ownership interest to be purchased based on targets met					3.00%	3.00%	3.00%						12.00%
Certificate of Deposit
Accounting Policies [Line Items]
Purchases of short-term investments									$ 30,000,000
Class A common stock
Accounting Policies [Line Items]
Number of shares repurchased | shares											0			2,500,000
Average price of repurchased shares | $ / shares														$ 5.08
Aggregate purchase price of repurchased shares														$ 12,500,000
Employee Stock Options
Accounting Policies [Line Items]
Weighted average period for recognition of unrecognized compensation expense											1 year 2 months 12 days
Restricted Stock Units
Accounting Policies [Line Items]
Weighted average period for recognition of unrecognized compensation expense											1 year 4 months 24 days
Total unrecognized compensation expense related to grants of restricted stock units								$ 2,500,000			$ 2,500,000			2,500,000
Performance Restricted Stock Units
Accounting Policies [Line Items]
Share-based compensation expenses								0			$ 0
Vesting period											3 years
Minimum | Employee Stock Options
Accounting Policies [Line Items]
Vesting period											1 year
Minimum | Restricted Stock Units
Accounting Policies [Line Items]
Vesting period											1 year
Minimum | Performance Restricted Stock Units
Accounting Policies [Line Items]
Share award grant percentage											0.00%
Maximum | Employee Stock Options
Accounting Policies [Line Items]
Vesting period											4 years
Maximum | Restricted Stock Units
Accounting Policies [Line Items]
Vesting period											4 years
Maximum | Performance Restricted Stock Units
Accounting Policies [Line Items]
Share award grant percentage											200.00%
Univision
Accounting Policies [Line Items]
Expiry year of long-term affiliation agreements											2021
Renewal period of affiliation agreements											2 years
Affiliate advertising minutes per hour for which entity has right to sell											6 minutes
Payment of sales representation fees to television stations								2,600,000		$ 2,400,000	$ 7,400,000	$ 6,800,000
Period to grant television station for terms of retransmission consent agreements											6 years
Retransmission consent agreements expiring date											Dec. 31, 2014
Retransmission consent agreements extended expiration date											Nov. 30, 2016
Amount due from television stations for carriage								$ 5,100,000			$ 5,100,000			$ 5,100,000
Common stock percentage held by Univision								10.00%			10.00%			10.00%
UniMas
Accounting Policies [Line Items]
Affiliate advertising minutes per hour for which entity has right to sell											4 minutes 30 seconds