Debt Arrangements - Additional Information (Detail)											1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended
		Mar. 15, 2018 USD ($)	Mar. 14, 2018 USD ($)	Feb. 22, 2018 USD ($) d	Nov. 02, 2017 USD ($)	Oct. 27, 2017 USD ($)	Aug. 18, 2017 USD ($)	Aug. 02, 2017 USD ($)	Mar. 18, 2013 USD ($)	Nov. 29, 2012 USD ($)	Jul. 31, 2017 USD ($)	Feb. 28, 2015 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) shares	Jul. 31, 2019	Mar. 31, 2019	Mar. 14, 2019 USD ($)	Feb. 12, 2018 USD ($)	Nov. 24, 2017 USD ($)	Oct. 26, 2017 USD ($)	Jun. 21, 2013 USD ($)
Debt Instrument [Line Items]
Principal amount of long term debt						$ 240,700,000
Percentage of conversion of convertible notes														5.75%			5.75%
Net proceeds received from issuance of debt																	$ 95,700,000
Debt service coverage ratio																						110.00%
Debt issue discount costs						$ 9,300,000
Current portion of long-term debt													$ 61,417,000			$ 61,417,000		$ 54,263,000
Restricted cash													15,134,000			15,134,000		16,026,000
Leverage ratio						450.00%
Net proceeds from Permitted Capital Raising Transactions						$ 100,000,000
Repayment of remaining outstanding principal balance						231,000,000										5,000,000
Deferred financing costs						$ 5,400,000
Long term debt, fair value													35,066,000			35,066,000		48,076,000
Principal outstanding balance	[1],[2]												$ 645,099,000			$ 645,099,000		675,229,000
Gain on extinguishment of debt																	$ 4,473,000
Maximum
Debt Instrument [Line Items]
Leverage ratio						575.00%
Aggregate amount of term loan facility						$ 165,700,000
1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Percentage of conversion of convertible notes														1.50%			1.50%
5.75% Senior Subordinated Notes Due August 2023
Debt Instrument [Line Items]
Percentage of conversion of convertible notes													5.75%	5.75%		5.75%	5.75%						5.75%
5.75% Senior Subordinated Notes Due August 2023 | Common Stock
Debt Instrument [Line Items]
Notes converted into common stock | shares													56,000			3,727,000	1,104,000
MG Icon
Debt Instrument [Line Items]
Equity ownership percentage										50.00%
Hardy Way, LLC
Debt Instrument [Line Items]
Joint venture ownership percentage										85.00%
Zoo York brand
Debt Instrument [Line Items]
Ownership Percentage										100.00%
IBG Borrower
Debt Instrument [Line Items]
Termination of license generating with minimum royalty guarantees								$ 500,000
IBG Borrower | Minimum
Debt Instrument [Line Items]
Asset coverage ratio, minimum								125.00%
IBG Borrower | Maximum
Debt Instrument [Line Items]
Leverage ratio								450.00%
2012 Senior Secured Notes
Debt Instrument [Line Items]
Principal amount of long term debt										$ 600,000,000
Percentage of conversion of convertible notes										4.229%
Debt instrument, quarterly payment										$ 10,500,000
Debt instrument, frequency of payment																quarterly
Variable Funding Notes
Debt Instrument [Line Items]
Principal amount of long term debt										100,000,000			$ 100,000,000			$ 100,000,000
Net proceeds received from issuance of debt												$ 100,000,000
Line of credit, outstanding													100,000,000			100,000,000
Debt Instrument anticipated repayment year and month							2020-01
L/C commitment and the swingline commitment							$ 0
Non cash additional interest expense on convertible notes													1,100,000	$ 1,000,000		$ 3,200,000	$ 2,900,000
2013 Senior Secured Notes
Debt Instrument [Line Items]
Principal amount of long term debt																											$ 275,000,000
Percentage of conversion of convertible notes																											4.352%
Debt instrument, quarterly payment										$ 4,800,000
Debt instrument, frequency of payment																quarterly
Senior Secured Notes
Debt Instrument [Line Items]
Principal amount of long term debt													445,900,000			$ 445,900,000		465,500,000
Debt Instrument anticipated repayment year and month										2020-01
Debt instrument, Maturity Date										2043-01
Debt instrument description of interest																If the Co-Issuers have not repaid or refinanced the Securitization Notes prior to January 2020 (the “anticipated repayment date”), additional interest will accrue on amounts outstanding under the Securitization Notes at a rate equal to (A) in respect of the Variable Funding Notes, 5% per annum, (B) in respect of the 2012 Senior Secured Notes and the 2013 Senior Secured Notes, the greater of (1) 5% per annum and (2) a per annum interest rate equal to the excess, if any, by which the sum of (x) the yield to maturity (adjusted to a quarterly bond-equivalent basis), on the anticipated repayment date of the United States treasury security having a term closest to 10 years plus (y) 5% per annum plus (z) with respect to the 2012 Senior Secured Notes, 3.4% per annum, or with respect to the 2013 Senior Secured Notes, 3.14% per annum, exceeds the original interest rate.
Additional interest rate										5.00%
Anticipated repayment date										10 years
Mandatory principal prepayment											$ 152,200,000
Debt issue discount costs											2,000,000
Prepayment penalty											300,000
Current portion of long-term debt													42,100,000			$ 42,100,000		42,700,000
Restricted cash													14,200,000			14,200,000		15,200,000
Cash interest expense for convertible notes													5,200,000	5,600,000		16,000,000	16,800,000
2012 Senior Secured Notes
Debt Instrument [Line Items]
Excess interest rate on original interest rate										3.40%
Debt instrument, decrease in quarterly principal payments											7,300,000
2013 Senior Secured Notes
Debt Instrument [Line Items]
Excess interest rate on original interest rate										3.14%
Debt instrument, decrease in quarterly principal payments											$ 3,400,000
Senior Secured Term Loan
Debt Instrument [Line Items]
Principal amount of long term debt						57,800,000		$ 300,000,000					182,700,000			182,700,000										$ 300,000,000
Debt issue discount costs																14,500,000		18,300,000
Current portion of long-term debt													19,300,000			19,300,000		11,600,000
Cash interest expense for convertible notes													4,600,000	4,500,000		13,700,000	12,500,000
Non cash additional interest expense on convertible notes													1,400,000	1,300,000		4,100,000	3,000,000
Maturity date of credit agreement								Aug. 02, 2022
Margin applied to LIBOR								7.00%
Percentage of principal debt quarterly amortization								0.50%
Principal debt quarterly amortization commencement date								Sep. 30, 2017
Estimated principal payments																									$ 12,000,000
Interest rate increase additional per annum			3.00%
Payment of unpaid principal and accrued interest of lenders			50.00%
Principal amount of long term debt													168,200,000			168,200,000		171,100,000
Senior Secured Term Loan | IBG Borrower
Debt Instrument [Line Items]
Equity ownership percentage			35.00%
Premium percentage of aggregate principal amount first year loan			5.00%
Premium percentage of aggregate principal amount second year loan			3.00%
Convertible Notes
Debt Instrument [Line Items]
Percentage of conversion of convertible notes															1.50%
Cash from escrow deposit returned to lenders						231,000,000
Payment from Escrow Account to acquire convertible notes															$ 59,200,000
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Principal amount of long term debt				$ 125,000,000					$ 400,000,000
Percentage of conversion of convertible notes				1.50%					1.50%										1.50%	1.50%
Net proceeds received from issuance of debt									$ 390,600,000
Cash interest expense for convertible notes														0			700,000
Non cash additional interest expense on convertible notes														$ 0			$ 2,400,000
Repayment of remaining outstanding principal balance		$ 111,200,000
Debt instrument, par value of notes repurchased																			$ 58,900,000	$ 104,900,000
Debt instrument, cash paid to repurchase convertible notes																			$ 59,300,000	$ 36,700,000
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018 | Common Stock
Debt Instrument [Line Items]
Debt instrument, shares issued to repurchase convertible notes | shares																				700,000
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023
Debt Instrument [Line Items]
Principal amount of long term debt				$ 125,000,000									$ 94,400,000			$ 94,400,000		$ 109,700,000
Percentage of conversion of convertible notes				5.75%									5.75%	5.75%		5.75%	5.75%	5.75%
Cash interest expense for convertible notes													$ 1,400,000	$ 1,600,000		$ 4,300,000	$ 3,900,000
Maturity date of credit agreement				Aug. 15, 2023
Debt instrument, conversion rate																52.1919
Principal amount of each convertible note													$ 1,000			$ 1,000
Convertible notes, initial conversion price per share | $ / shares													$ 19.16			$ 19.16
Debt instrument convertible conversion price as percentage upon automatic conversion				5.75%
Debt instrument convertible conversion price as percentage upon mandatory conversion				5.75%
Debt instrument, convertible, threshold trading days | d				10
Volume weighted average price description																If the Company elects to pay all or a portion of a Conversion Make-Whole Payment in shares of common stock, the number of shares of common stock payable will be equal to the applicable Conversion Make-Whole Payment divided by the average of the 10 individual volume-weighted average prices for the 10-trading day period immediately preceding the applicable conversion date.
Debt instrument, convertible, threshold consecutive trading days | d				30
Debt instrument, redemption price, percentage				100.00%
Debt instrument, redemption, description																each holder will have the right, at its option, to require the Company to repurchase for cash all or a portion of such holder’s 5.75% Convertible Notes at a fundamental change purchase price equal to 100% of the principal amount of the 5.75% Convertible Notes to be repurchased, together with interest accrued and unpaid to, but excluding, the fundamental change purchase date.
Debt instrument, restrictive covenants																The Company is subject to certain restrictive covenants pursuant to the 5.75% Convertible Note Indenture, including limitations on (i) liens, (ii) indebtedness, (iii) asset sales, (iv) restricted payments and investments, (v) prepayments of indebtedness and (vi) transactions with affiliates.
Debt conversion original debt amount													$ 200,000			$ 15,300,000
Notes converted into common stock | shares																800,000
Stock issued pursuant to conversion settlement | shares																2,900,000
Long term debt, fair value													35,100,000			$ 35,100,000		$ 48,100,000
Principal outstanding balance													94,400,000			94,400,000		109,700,000
Gain on extinguishment of debt																	$ 4,500,000
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023 | Fair Value Option
Debt Instrument [Line Items]
Long term debt, fair value													35,100,000			35,100,000		$ 48,100,000
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023 | Other Income
Debt Instrument [Line Items]
Income (loss) on conversion of debt													$ (100,000)			$ (10,600,000)
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023 | Maximum
Debt Instrument [Line Items]
Notes converted into common stock | shares													100,000
Stock issued pursuant to conversion settlement | shares													100,000
First Delayed Draw Term Loan
Debt Instrument [Line Items]
Debt issue discount costs					$ 1,000,000
Aggregate amount of term loan facility					25,000,000	$ 25,000,000
Aggregate amount of term loan received in cash					$ 24,000,000
Second Delayed Draw Term Loan
Debt Instrument [Line Items]
Aggregate amount of term loan facility																							$ 140,700,000
Second Delayed Draw Term Loan | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Percentage of conversion of convertible notes			1.50%
Maturity date of credit agreement			Mar. 15, 2018
Aggregate amount of term loan facility			$ 110,000,000
Senior Secured Term Loan Due 2022 | Minimum
Debt Instrument [Line Items]
Amortization rate per annum						2.00%
Senior Secured Term Loan Due 2022 | Maximum
Debt Instrument [Line Items]
Amortization rate per annum																					10.00%
5.75% Senior Subordinated Notes Due August 2023
Debt Instrument [Line Items]
Estimated principal payments																								$ 6,100,000
5.75% Senior Subordinated Notes Due August 2023 | Maximum
Debt Instrument [Line Items]
Percentage of conversion of convertible notes																								5.75%

[1] Carrying amounts include aggregate unamortized debt discount and debt issuance costs.

[2] Includes the 5.75% Convertible Notes accounted for under the fair value option. See to Note 7.