Discontinued Operations - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 27, 2017	Jul. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	May 09, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Amortization of convertible note discount					$ 7,574,000	$ 13,225,000
Write-off of deferred financing costs	$ 9,300,000
Senior Secured Term Loan
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Amortization of convertible note discount			$ 1,300,000	$ 500,000	3,000,000	500,000
Write-off of deferred financing costs					$ 19,500,000		$ 8,000,000
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
Interest expense				0
Prepayment premium				2,308,000		31,554,000
Transaction costs				200,000
Pre-tax gain on sale of Entertainment segment				104,100,000
Operating Segments | Entertainment | ASC 205-20-45-6
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Interest expense				6,500,000		12,900,000
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
Mandatory principal prepayment		$ 152,200,000
Prepayment premium						15,200,000
Write-off of deferred financing costs						9,400,000
Write-off of original issue discount						$ 4,700,000
Operating Segments | Entertainment | Securitization Notes
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Prepayment penalty				300,000
Write-off of deferred financing costs				$ 2,000,000