Revenue - Schedule of Change Due to Topic 606 Adoption (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Deficit
Accumulated deficit		$ (1,709,747)				$ (1,611,334)				$ (1,709,747)	$ (1,611,334)
Revenues
Revenues		261,000	$ 621,180	$ 477,210	$ 128,193	269,503	$ 619,820	$ 445,420	$ 128,964	1,487,583	1,463,707	$ 1,359,074
Sponsorship, international agreements and accommodations										97,361	100,116
Costs and expenses
Income tax expense										91,942	95,855	16,026
Net income attributable to Six Flags Entertainment Corporation		$ (11,155)	$ 179,833	$ 79,519	$ (69,132)	$ 79,422	$ 184,417	$ 74,502	$ (62,345)	179,065	275,996	$ 273,816
Calculated under Revenue Guidance in Effect before Topic 606
Revenues
Sponsorship, international agreements and accommodations										97,224	101,058
Costs and expenses
Income tax expense										91,913	96,053
Net income attributable to Six Flags Entertainment Corporation										178,957	276,740
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Stockholders' Deficit
Accumulated deficit	$ 4,900
Revenues
Revenues										100	(900)
Sponsorship, international agreements and accommodations										137	(942)
Costs and expenses
Income tax expense	$ 1,300									29	(198)
Net income attributable to Six Flags Entertainment Corporation										$ 108	$ (744)