Discontinued Operations - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	May 09, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Amortization of convertible note discount				$ 13,225,000	$ 17,789,000
Senior Secured Term Loan
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Write-off of deferred financing costs				1,700,000		$ 2,100,000
Operating Segments | Entertainment
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Sell price of business							$ 349,100,000
Pre-tax gain on sale of Entertainment segment		$ 104,100,000		104,100,000
Transaction costs		200,000		7,800,000
Interest expense		0	$ 6,500,000	12,900,000	14,500,000
Prepayment premium		2,308,000		31,554,000
Operating Segments | Entertainment | Senior Secured Term Loan
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Amortization of convertible note discount			$ 1,000,000	1,700,000	$ 1,900,000
Mandatory principal prepayment	$ 152,200,000
Write-off of deferred financing costs		2,000,000		9,400,000
Write-off of original issue discount				4,700,000
Prepayment premium				$ 15,200,000
Prepayment penalty		$ 300,000