Commitments and Contingencies (Details)			1 Months Ended		12 Months Ended
	Jan. 07, 2016 USD ($)	Apr. 01, 1998 USD ($)	May 31, 2019 USD ($) shares	May 31, 2017 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) multiple	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) claim	Apr. 07, 2017 item
Details of commitments and contingencies
Acquisition of capital stock of the former Six Flags Entertainment Corporation, paid in cash		$ 976,000,000.0
Redemption value of noncontrolling interests						$ 529,300,000
Additions to property and equipment						143,913,000	$ 135,624,000	$ 135,219,000
Total loans receivable from the partnerships that own partnership parks						239,300,000
Number of questions certified for consideration by appellate court | item									2
Number of claims filed | claim								4
Minimum
Details of commitments and contingencies
Range of possible loss per aggrieved party	$ 1,000							$ 100
Maximum
Details of commitments and contingencies
Range of possible loss per aggrieved party	$ 5,000							$ 1,000
Multi-layered general liability policies
Details of commitments and contingencies
Excess liability coverage per occurrence						100,000,000.0
Self-insured retention per occurrence						2,000,000.0
Deductible per occurrence applicable to all claims in the policy year						500,000
Workers' compensation claims
Details of commitments and contingencies
Deductible per occurrence applicable to all claims in the policy year						0.75
Information security and privacy liability insurance policy
Details of commitments and contingencies
Self-insured retention per occurrence						0.25
Insurance value maintained						10.0
Amended And Restated Term Loan B
Details of commitments and contingencies
Additional contingent borrowing capacity						$ 350,000,000.0
Six Flags over Georgia
Details of commitments and contingencies
Limited partner interests owned (as a percent)						31.00%
Remaining redeemable units (as a percent)						69.00%
Six Flags over Texas
Details of commitments and contingencies
Limited partner interests owned (as a percent)						53.20%
Units purchased in partnership parks (in units) | shares			0.100
Units purchased in partnership parks			$ 200,000
Remaining redeemable units (as a percent)						46.80%
Six Flags over Texas and Georgia
Details of commitments and contingencies
Share of Partnership Parks' annual distributions paid to Six Flags Entertainment Corporation						$ 32,500,000
Rolling period for making minimum capital expenditure at each of the Partnership Parks						5 years
Percentage of capital expenditures to Partnership Parks' revenues						6.00%
Weighted average period of the park's EBITDA for calculation of value of purchase price						4 years
Additions to property and equipment						$ 21,800,000
Cash generated from operating activities by partnerships, after deduction of capital expenditures and excluding the impact of short-term intercompany advances						$ 79,300,000
Six Flags over Georgia
Details of commitments and contingencies
Specified multiple for purchase price valuation (in multipliers) | multiple						8.0
Specified price for purchase of partnership parks						$ 409,700,000
Six Flags over Texas
Details of commitments and contingencies
Specified multiple for purchase price valuation (in multipliers) | multiple						8.5
Specified price for purchase of partnership parks						$ 527,300,000
Units purchased in partnership parks (in units) | shares				0.175
Units purchased in partnership parks				$ 400,000
Scenario, Forecast | Six Flags over Texas and Georgia
Details of commitments and contingencies
Annual distributions by general partners to limited partners in partnership parks					$ 74,200,000
Additions to property and equipment					$ 24,800,000