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Carrying amount as of the balance sheet date of obligations due all related parties.

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The amount for notes payable (written promise to pay), due to related parties.

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Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due within 1 year (or 1 business cycle).

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RELATED PARTY TRANSACTIONS WITH IAC - Narrative (Details) € in Millions, £ in Millions, shares in Millions				3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 26, 2017 EUR (€)	Oct. 14, 2016 USD ($)	Aug. 29, 2013 USD ($)	Mar. 31, 2019 USD ($)	Sep. 29, 2017 USD ($) intercompany_note	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 EUR (€) shares	Dec. 31, 2017 USD ($) shares	Mar. 20, 2017 USD ($) subsidiary	Mar. 20, 2017 GBP (£) subsidiary	Feb. 07, 2017 GBP (£)
Related Party Transaction [Line Items]
Proceeds from issuance of related party debt						$ 0	$ 0		$ 131,360,000
Services Agreement
Related Party Transaction [Line Items]
Term of related party agreement						1 year
Automatic renewal periods for related party agreement						1 year
Employee Matters Agreement
Related Party Transaction [Line Items]
Voting interest (as a percent)						80.00%
IAC
Related Party Transaction [Line Items]
Expenses from transactions with related party				$ 11,400,000
Allocated general and administrative costs from related party activities					$ 4,789,000		4,800,000
Long-term debt—related party							1,015,000
IAC \| Notes Payable \| Promissory note due October 14, 2023
Related Party Transaction [Line Items]
Long-term debt—related party		$ 42,000,000.0
Proceeds from issuance of related party debt		$ 11,400,000
Long-term debt, interest rate		11.00%
IAC \| Notes Payable \| Promissory Note Due March 20, 2024 (Note A)
Related Party Transaction [Line Items]
Long-term debt—related party \| £											£ 21.0
Long-term debt, interest rate										6.50%	6.50%
Number of foreign subsidiaries of related party issued long-term debt \| subsidiary										2	2
IAC \| Notes Payable \| Promissory Note Due March 20, 2047 (Note B)
Related Party Transaction [Line Items]
Long-term debt—related party										$ 15,500,000
Long-term debt, interest rate										7.00%	7.00%
Number of foreign subsidiaries of related party issued long-term debt \| subsidiary										2	2
IAC \| Notes Payable \| Promissory Note Due February 7, 2024
Related Party Transaction [Line Items]
Long-term debt—related party \| £												£ 8.4
Long-term debt, interest rate												6.875%
IAC \| Notes Payable \| Promissory note due August 29, 2018
Related Party Transaction [Line Items]
Long-term debt—related party			$ 5,000,000.0
Basis spread on variable rate (as a percent)			2.00%
IAC \| Notes Payable \| Related Party Promissory Note
Related Party Transaction [Line Items]
Increase (decrease) in long-term debt - related parties \| €	€ (2.4)
IAC \| Notes Payable \| Promissory Note Due December 31, 2020
Related Party Transaction [Line Items]
Increase (decrease) in long-term debt - related parties							(1,000,000.0)	€ (0.9)
IAC \| Services Agreement
Related Party Transaction [Line Items]
Payments received from related parties						$ 4,800,000	5,700,000		$ 1,700,000
Amounts due from related party						0
Amounts due to related party						0	100,000
IAC \| Tax Sharing Agreement
Related Party Transaction [Line Items]
Taxes payable						$ 200,000	$ 12,100,000
IAC \| Employee Matters Agreement
Related Party Transaction [Line Items]
Shares received from related party pursuant to employee matters agreement (in shares) \| shares						0.5	0.9	0.9	0.4
IAC \| Sublease Agreement
Related Party Transaction [Line Items]
Payments received from related parties						$ 1,400,000
Amounts due from related party						$ 900,000
IAC \| Intercompany Notes
Related Party Transaction [Line Items]
Number of related party debt instruments \| intercompany_note					2
IAC \| Payoff Intercompany Note
Related Party Transaction [Line Items]
Current notes receivable, related parties					$ 61,500,000
IAC \| Working Capital Intercompany Note
Related Party Transaction [Line Items]
Current notes receivable, related parties					$ 15,000,000