Debt and Finance Lease Obligations - Narrative (Details) $ in Thousands, € in Millions, kr in Millions					9 Months Ended	12 Months Ended
		Jul. 30, 2021 USD ($)	Jan. 08, 2021	Aug. 05, 2020 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 ISK (kr)	Dec. 29, 2020 ISK (kr)	Oct. 15, 2020 ISK (kr)	Aug. 31, 2020 USD ($)	Feb. 15, 2019 USD ($)	Feb. 15, 2019 EUR (€)
Line Of Credit Facility [Line Items]
Write off unamortized debt					$ 15,525	$ 2,737
Fees				$ 9,200
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Borrowing capacity on line of credit										$ 450,000
FlyOver Iceland Credit Facility
Line Of Credit Facility [Line Items]
Maturity date			Sep. 01, 2023		Mar. 01, 2022
Credit facility	[1]				$ 5,619	5,820
Line of credit facility maximum borrowing capacity											$ 5,600	€ 5.0
Line Of Credit Facility Amendment Description					an addendum to the FlyOver Iceland Credit Facility effective January 8, 2021 wherein the principal payments were deferred for twelve months beginning December 1, 2020, with the first payment due December 1, 2021. The addendum also extended the maturity date to September 1, 2023. There were no other changes to the terms of the FlyOver Iceland Credit Facility
Line Of Credit Facility Date Of First Required Payment			Dec. 01, 2021
Fly Over Iceland Term Loan
Line Of Credit Facility [Line Items]
Credit facility	[1]				$ 689	705
Line of credit facility maximum borrowing capacity						700	kr 90.0
2018 Credit Agreement
Line Of Credit Facility [Line Items]
Write off unamortized debt					2,100
2018 Credit Agreement | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maturity date		Oct. 24, 2023
Credit facility						$ 266,762
2018 Credit Agreement | Term Loan B
Line Of Credit Facility [Line Items]
Loans Proceeds Offset		$ 400,000
Fees		14,800
2021 Credit Facility
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity		500,000
Loans Proceeds Offset		400,000
Fees		$ 14,800
2021 Credit Facility | London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Interest rate description		5.00%, with a LIBOR floor of 0.50%
2021 Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Minimum liquidity requirement		$ 75,000
Remaining borrowing capacity on line of credit					78,200
Line of credit facility maximum borrowing capacity		$ 100,000
Maturity date		July 30, 2026
2021 Credit Facility | Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Financial covenants leverage ratio step up		400.00%
Leverage ratio		450.00%
Debt covenant, interest coverage ratio		250.00%
2021 Credit Facility | Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Interest coverage ratio		200.00%
2021 Credit Facility | Senior Secured Credit Facility
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity		$ 500,000
2021 Credit Facility | Term Loan B
Line Of Credit Facility [Line Items]
Borrowing capacity on line of credit		400,000
Letters of Credit Outstanding					21,800
Line of credit facility maximum borrowing capacity		$ 400,000
Maturity date		July 30, 2028
2021 Credit Facility | Term Loan B | Borrowings
Line Of Credit Facility [Line Items]
Credit facility					$ 400,000
First Term Loan | Fly Over Iceland Term Loan
Line Of Credit Facility [Line Items]
Maturity date						Apr. 01, 2023
Line of credit facility maximum borrowing capacity | kr									kr 10.0
Line Of Term Loan Amendment Description						bears interest on a seven-day term deposit at the Central Bank of Iceland
Second Term Loan | Fly Over Iceland Term Loan
Line Of Credit Facility [Line Items]
Maturity date						Oct. 01, 2024
Line of credit facility maximum borrowing capacity | kr									kr 30.0
Line Of Term Loan Amendment Description						bears interest on a seven-day term deposit at the Central Bank of Iceland plus 3.07%
Third Term Loan | Fly Over Iceland Term Loan
Line Of Credit Facility [Line Items]
Maturity date						Feb. 01, 2023
Line of credit facility maximum borrowing capacity | kr								kr 50.0
Line Of Term Loan Amendment Description						bears interest at one-month Reykjavik InterBank Offered Rate (“REIBOR”) plus 4.99%. The Icelandic State Treasury guarantees supplemental loans provided by credit institutions to companies impacted by the COVID-19 pandemic. Accordingly, the Icelandic State Treasury guaranteed the repayment of up to 85% of the principal and interest on the ISK 10.0 million and ISK 30.0 million term loans and 70% of the principal amount on the ISK 50.0 million term loan

[1] Represents the weighted-average interest rate in effect at the respective periods, including any applicable margin. The interest rates do not include amortization of debt issuance costs or commitment fees.