Six Flags Entertainment 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity Registrant Name	Six Flags Entertainment Corporation
Entity File Number	1-13703
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3995059
Entity Address, Address Line One	1000 Ballpark Way, Suite 400
Entity Address, City or Town	Arlington
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	76011
City Area Code	972
Local Phone Number	595-5000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 1,628.2
Entity Common Stock, Shares Outstanding		85,172,488
Entity Central Index Key	0000701374
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Common stock
Document and Entity Information
Title of 12(b) Security	Common stock, $0.025 par value per share
Trading Symbol	SIX
Security Exchange Name	NYSE
Preferred Stock
Document and Entity Information
Title of 12(b) Security	Preferred Stock Purchase Rights
Trading Symbol	SIX
Security Exchange Name	NYSE

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 157,760	$ 174,179
Accounts receivable, net	36,610	108,679
Inventories	39,191	32,951
Prepaid expenses and other current assets	73,179	60,431
Total current assets	306,740	376,240
Property and equipment, net:
Property and equipment, at cost	2,408,690	2,345,283
Accumulated depreciation	(1,157,403)	(1,061,287)
Total property and equipment, net	1,251,287	1,283,996
Other assets:
Right-of-use operating leases, net	196,711	201,128
Debt issuance costs	7,034	3,624
Deposits and other assets	7,103	12,722
Goodwill	659,618	659,618
Intangible assets, net of accumulated amortization	344,198	345,212
Total other assets	1,214,664	1,222,304
Total assets	2,772,691	2,882,540
Current liabilities:
Accounts payable	26,582	32,904
Accrued compensation, payroll taxes and benefits	22,031	19,556
Accrued insurance reserves	31,060	35,376
Accrued interest payable	60,184	26,128
Other accrued liabilities	93,369	63,019
Deferred revenue	205,125	144,040
Current portion of long-term debt		8,000
Short-term lease liabilities	14,054	10,709
Total current liabilities	452,405	339,732
Noncurrent liabilities:
Long-term debt	2,622,641	2,266,884
Long-term lease liabilities	187,432	188,149
Other long-term liabilities	43,553	27,514
Deferred income taxes	101,831	247,121
Total noncurrent liabilities	2,955,457	2,729,668
Total liabilities	3,407,862	3,069,400
Redeemable noncontrolling interests	523,376	529,258
Stockholders' deficit:
Preferred stock, $1.00 par value
Common stock, $0.025 par value, 280,000,000 shares authorized; 85,075,901 and 84,633,845 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively	2,126	2,116
Capital in excess of par value	1,089,199	1,066,223
Accumulated deficit	(2,153,368)	(1,709,747)
Accumulated other comprehensive loss, net of tax	(96,504)	(74,710)
Total stockholders' deficit	(1,158,547)	(716,118)
Total liabilities and stockholders' deficit	$ 2,772,691	$ 2,882,540

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Common stock, par value (in dollars per share)	$ 0.025	$ 0.025
Common stock, shares authorized (in shares)	280,000,000	280,000,000
Common stock, shares issued (in shares)	85,075,901	84,633,845
Common stock, shares outstanding (in shares)	85,075,901	84,633,845

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total revenues	$ 356,575	$ 1,487,583	$ 1,463,707
Operating expenses (excluding depreciation and amortization shown separately below)	389,726	607,791	574,724
Selling, general and administrative expenses (including stock-based compensation of $19,530 and $13,274 in 2020 and 2019, respectively, and a net reversal of stock-based compensation of $46,684 in 2018, and excluding depreciation and amortization shown separately below)	147,295	199,194	132,168
Costs of products sold	34,119	130,304	121,803
Other net periodic pension benefit	(5,190)	(4,186)	(5,169)
Depreciation	119,159	115,825	113,246
Amortization	1,014	2,405	2,447
Loss on disposal of assets	7,689	2,162	1,879
Interest expense	155,411	114,703	108,034
Interest income	(688)	(1,401)	(791)
Loss on debt extinguishment	6,106	6,484	0
Other expense, net	24,993	2,542	3,508
(Loss) income before income taxes	(523,059)	311,760	411,858
Income tax (benefit) expense	(140,967)	91,942	95,855
Net (loss) income	(382,092)	219,818	316,003
Less: Net income attributable to noncontrolling interests	(41,288)	(40,753)	(40,007)
Net (loss) income attributable to Six Flags Entertainment Corporation	$ (423,380)	$ 179,065	$ 275,996
Weighted-average common shares outstanding:
Weighted-average common shares outstanding-basic (in shares)	84,800	84,348	84,100
Weighted-average common shares outstanding - diluted (in shares)	84,800	84,968	85,445
Net (loss) earnings per average common share outstanding:
Net (loss) earnings per average common share outstanding - basic (in dollars per share)	$ (4.99)	$ 2.12	$ 3.28
Net (loss) earnings per average common share outstanding - diluted (in dollars per share)	(4.99)	2.11	3.23
Cash dividends declared per common share	$ 0.25	$ 3.29	$ 3.16
Park admissions
Total revenues	$ 202,646	$ 815,782	$ 810,064
Park food, merchandise and other
Total revenues	126,306	574,440	553,527
Sponsorship international agreements and accommodations
Total revenues	$ 27,623	$ 97,361	$ 100,116

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Operations
Stock-based compensation	$ 19,530	$ 13,274	$ (46,684)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income (Loss)
Net (loss) income	$ (382,092)	$ 219,818	$ 316,003
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustment	(4,053)	4,081	1,161
Defined benefit retirement plan	(6,259)	(6,167)	661
Change in cash flow hedging	(11,482)	(1,126)
Other comprehensive (loss) income, net of tax	(21,794)	(3,212)	1,822
Comprehensive (loss) income	(403,886)	216,606	317,825
Less: Comprehensive income attributable to noncontrolling interests	(41,288)	(40,753)	(40,007)
Comprehensive (loss) income attributable to Six Flags Entertainment Corporation	$ (445,174)	$ 175,853	$ 277,818

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income (Loss)
Foreign currency translation adjustment, tax expense (benefit)	$ (1.2)	$ 1.1	$ 0.3
Defined benefit retirement plan, tax expense (benefit)	(2.1)	(2.1)	$ 0.2
Derivatives qualifying as hedges, tax expense (benefit)	$ (3.8)	$ (0.4)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands	Common stockCumulative Effect, Period of Adoption, Adjusted Balance	Common stock	Capital in excess of par valueCumulative Effect, Period of Adoption, Adjusted Balance	Capital in excess of par value	Accumulated deficitCumulative Effect, Period of Adoption, Adjustment	Accumulated deficitCumulative Effect, Period of Adoption, Adjusted Balance	Accumulated deficit	Accumulated other comprehensive lossCumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive lossCumulative Effect, Period of Adoption, Adjusted Balance	Accumulated other comprehensive loss	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Total
Beginning balance (Accounting Standards Update 2014-09 and 2018-02) at Dec. 31, 2017					$ 4,557			$ (9,439)			$ (4,882)
Beginning balance at Dec. 31, 2017	$ 2,112	$ 2,112	$ 1,086,265	$ 1,086,265		$ (1,525,051)	$ (1,529,608)		$ (73,320)	$ (63,881)		$ (509,994)	$ (505,112)
Beginning balance (in shares) at Dec. 31, 2017	84,488,433	84,488,433
Increase (Decrease) in Stockholders' Deficit
Issuance of common stock		$ 31		41,626									41,657
Issuance of common stock (in shares)		1,264,497
Stock-based compensation				(46,684)									(46,684)
Dividends declared to common shareholders							(265,755)						(265,755)
Repurchase of common stock		$ (45)		(14,341)			(96,604)						(110,990)
Repurchase of common stock (in shares)		(1,827,991)
Employee stock purchase plan		$ 1		2,047									2,048
Employee stock purchase plan (in shares)		37,243
Fresh start valuation adjustment for partnership park units purchased							80						80
Change in redemption value of partnership units				(31,273)									(31,273)
Net income (loss) attributable to Six Flags Entertainment Corporation							275,996						275,996
Other comprehensive income (loss), net of tax										1,822			1,822
Ending balance at Dec. 31, 2018		$ 2,099		1,037,640			(1,611,334)			(71,498)			(643,093)
Ending balance (in shares) at Dec. 31, 2018		83,962,182
Increase (Decrease) in Stockholders' Deficit
Issuance of common stock		$ 16		17,480									17,496
Issuance of common stock (in shares)		622,787
Stock-based compensation				13,274									13,274
Dividends declared to common shareholders							(277,523)						(277,523)
Repurchase of common stock				(52)									(52)
Repurchase of common stock (in shares)		(882)
Employee stock purchase plan		$ 1		2,130									2,131
Employee stock purchase plan (in shares)		49,758
Fresh start valuation adjustment for partnership park units purchased							45						45
Change in redemption value of partnership units				(4,249)									(4,249)
Net income (loss) attributable to Six Flags Entertainment Corporation							179,065						179,065
Other comprehensive income (loss), net of tax										(3,212)			(3,212)
Ending balance at Dec. 31, 2019		$ 2,116		1,066,223			(1,709,747)			(74,710)			(716,118)
Ending balance (in shares) at Dec. 31, 2019		84,633,845
Increase (Decrease) in Stockholders' Deficit
Issuance of common stock		$ 8		2,237									2,245
Issuance of common stock (in shares)		371,182
Stock-based compensation				19,530									19,530
Dividends declared to common shareholders							(21,165)						(21,165)
Repurchase of common stock				(54)									(54)
Repurchase of common stock (in shares)		(2,291)
Employee stock purchase plan		$ 2		1,281									1,283
Employee stock purchase plan (in shares)		73,165
Fresh start valuation adjustment for partnership park units purchased							924						924
Change in redemption value of partnership units				(18)									(18)
Net income (loss) attributable to Six Flags Entertainment Corporation							(423,380)						(423,380)
Other comprehensive income (loss), net of tax										(21,794)			(21,794)
Ending balance at Dec. 31, 2020		$ 2,126		$ 1,089,199			$ (2,153,368)			$ (96,504)			$ (1,158,547)
Ending balance (in shares) at Dec. 31, 2020		85,075,901

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net (loss) income	$ (382,092)	$ 219,818	$ 316,003
Adjustments to reconcile net (loss) income to net cash used in and provided by operating activities:
Depreciation and amortization	120,173	118,230	115,693
Stock-based compensation	19,530	13,274	(46,684)
Interest accretion on notes payable	1,157	1,310	1,344
Loss on debt extinguishment	6,106	6,484	0
Amortization of debt issuance costs	6,535	3,563	3,979
Other, including loss on disposal of assets	(4,028)	(1,029)	574
Gain on sale of investee	0	(724)	0
Deferred income taxes (benefit) expense	(134,199)	78,386	72,893
Change in accounts receivable	71,654	7,725	(39,193)
Change in inventories, prepaid expenses and other current assets	(19,452)	(14,709)	(3,769)
Change in deposits and other assets	5,604	(1,665)	1,633
Change in ROU operating leases	4,477	7,865	0
Change in accounts payable, deferred revenue, accrued liabilities and other long-term liabilities	79,075	(15,472)	(13,750)
Change in operating lease liabilities	524	(7,914)	0
Change in accrued interest payable	34,056	(4,569)	4,409
Net cash (used in) provided by operating activities	(190,880)	410,573	413,132
Cash flows from investing activities:
Additions to property and equipment	(100,878)	(143,913)	(135,624)
Property insurance recoveries	2,514	3,737	2,500
Acquisition of park assets, net of cash acquired	0	0	(19,059)
Proceeds from sale of assets	7,470	1,050	71
Net cash used in investing activities	(90,894)	(139,126)	(152,112)
Cash flows from financing activities:
Repayment of borrowings	(526,510)	(802,750)	(274,000)
Proceeds from borrowings	884,000	970,000	356,000
Payment of debt issuance costs	(24,987)	(9,911)	(793)
Payment of cash dividends	(22,499)	(278,951)	(267,044)
Proceeds from issuance of common stock	3,528	19,627	43,705
Stock repurchases	(54)	(52)	(110,990)
Reduction in finance lease liability	(493)	0	0
Purchase of redeemable noncontrolling interest	(4,976)	(217)	(353)
Distributions to noncontrolling interests	(41,288)	(40,753)	(40,007)
Net cash provided by (used in) financing activities	266,721	(143,007)	(293,482)
Effect of exchange rate on cash	(1,366)	1,131	(426)
Net increase (decrease) in cash and cash equivalents	(16,419)	129,571	(32,888)
Cash and cash equivalents at beginning of period	174,179	44,608	77,496
Cash and cash equivalents at end of period	157,760	174,179	44,608
Supplemental cash flow information
Cash paid for interest	99,239	114,398	98,302
Cash paid for income taxes	$ 5,917	$ 28,209	$ 30,009

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2020
Description of Business
Description of Business	1. Description of Business We own and operate regional theme parks and waterparks. We are the largest regional theme park operator in the world and the largest operator of waterparks in North America. Of the 26 parks we currently own or operate, 23 parks are located in the United States, two parks are located in Mexico and one park is located in Montreal, Canada. On April 1, 1998, we acquired the former Six Flags Entertainment Corporation ("Former SFEC", a corporation that has been merged out of existence and that has always been a separate corporation from the current Six Flags Entertainment Corporation ("Holdings")), which had operated regional theme parks and waterparks under the Six Flags name for nearly 40 years, and established an internationally recognized brand name. We own the "Six Flags" brand name in the United States and foreign countries throughout the world. To capitalize on this name recognition, 22 of our current parks are branded as "Six Flags" parks and beginning in 2014 we also began the development, with third-party partners, of Six Flags-branded parks outside of North America. COVID-19 Considerations In response to the COVID-19 pandemic, federal, state and local governments implemented significant restrictions on travel, social conduct and business operations, including mass quarantine and social distancing mandates and orders. On March 13, 2020, we temporarily suspended operations at all of our theme parks and waterparks due to the COVID-19 pandemic. During 2020, 20 of our 26 parks operated for portions of the season but several of our larger parks could not operate rides. Parks that did operate had capacity and other operating limitations. We quickly implemented plans to mitigate the impact of the COVID-19 pandemic on our business and ensure the health and safety of our employees and guests. In response to the challenging environment, we focused on the following actions: ● Implementing immediate cost controls by right-sizing marketing and temporarily reducing salaries of all full-time employees by 25% ; ● Strengthening liquidity through expansion of our revolving credit facility, suspension of testing of certain maintenance covenants in our credit facility, issuance of senior secured notes, and suspension of dividend payments and stock repurchase program; ● Enhancing financial flexibility by delaying or reducing capital expenses related new ride and attractions; ● Developing measures to preserve our season pass holders and members; ● Opening parks as quickly as possible, while following governmental and public health guidelines; and ● Creating new sources of revenue by introducing animal and holiday drive-thru experiences at many parks. ​ We resumed partial operations at many of our parks on a staggered basis near the end of the second quarter using a cautious and phased approach, including limiting attendance, in accordance with local conditions and government guidelines. Attendance trends in 2020 continued to improve throughout the year for the parks that were open. Several of our parks modified their operations by providing drive-through or walk-through experiences for the holiday season, and our parks in Mexico were able to operate for a portion of the fourth quarter. As a result, all of our theme parks and some of its water parks operated in at least some capacity for a portion of the season, albeit pursuant to reduced capacity and other operating limitations. Comparisons of open parks to prior year in the third quarter exclude attendance from Six Flags Discovery Kingdom and Six Flags Great America, as these parks had modified operations with minimal attendance in the third quarter of 2020. We have taken measures to ensure sufficient liquidity to meet our cash flow needs and covenant compliance obligations for at least the next twelve months from the issuance of the financial statements. Additionally, we believe we have sufficient liquidity to meet our cash obligations through the end of 2021 even if our open parks are required to close. In addition to reducing expenses including capital expenditures, in April 2020, we increased the revolving credit commitments under the Second Amended and Restated Revolving Loan by $131.0 million, increasing the facility from $350.0 million to $481.0 million. Also, in April, Six Flags Theme Parks Inc. (“SFTP”), Holdings’ indirect, wholly owned subsidiary, completed the private sale of $725.0 million in aggregate principal amount of 7.00% senior secured notes due 2025. In August 2020, we extended the increased revolving credit commitments under the Second Amended and Restated Revolving Loan through December 31, 2022 and extended the suspension of our senior secured leverage ratio financial maintenance covenant through the end of 2021. See Note 3, Long-Term Indebtedness, for more information on these transactions. In connection with the Second Amended and Restated Credit Agreement, we suspended our quarterly dividend payment and stock repurchase program until the earlier December 31, 2022, or such time as SFTP reduces the incremental revolving credit commitments by $131 million and begins using actual results to calculate covenant compliance. The COVID-19 pandemic continues to present material uncertainty and risk with respect to our performance and financial results, including the ability to open all of our parks to guests. We will continue to consider near-term exigencies and the long-term financial health of the business as clear steps are taken to mitigate the consequences of the COVID-19 pandemic. The extent to which the COVID-19 pandemic impacts our business will depend on future developments, which are highly uncertain and cannot be predicted, including additional actions taken to contain COVID-19 or treat its impact, among others. Our business and financial results could be materially and adversely impacted. Transformation Plan Prior to the pandemic, we initiated a transformation plan. The transformation plan consists of five revenue initiatives and three cost initiatives designed to improve our core operational effectiveness and to support our strategy, delivering sustainable value creation over time. Our strategy is to create thrilling, memorable experiences at our regional parks, delivered by a diverse and empowered team, through industry-leading innovation and technology. The strategy is driven by three focus areas: (i) modernizing the guest experience through technology, (ii) continuously improving operational efficiency, and (iii) driving financial excellence. We plan to focus on our core business over the next two to three years; during this time, we will be cautious about expanding into adjacent domestic markets or entering into new international agreements. Due to the outbreak of the COVID-19 pandemic in early 2020 and the resulting park closures, management redirected its focus on steering us through this crisis, causing a delay in our transformation plan. However, in the latter half of 2020, we made significant progress on each of the initiatives. We closed two satellite offices; reduced our full-time headcount costs; initiated centralized negotiations with several vendors to reduce procurement costs; and piloted a model to optimize park level variable labor. From a revenue perspective, we improved our menu assortment, pricing and merchandizing strategy; developed a new tool to optimize media spending; improved our website; and made progress on our initiative to attract more single day visitors. ​ ​ ​ ​ ​ Transformation Costs Breakout ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2020 Amounts included in "Other expense, net" ​ ​ ​ Consultant costs ​ $ 20,460 Employee termination costs ​ ​ 4,362 Amounts included in "Loss on disposal of assets" ​ ​ ​ Ride / asset write-offs ​ ​ 9,754 Total transformation costs ​ $ 34,576 ​

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies a. Basis of Presentation The consolidated financial statements include our accounts and the accounts of our wholly owned subsidiaries. We also consolidate the partnerships that own Six Flags Over Texas ("SFOT") and Six Flags Over Georgia (including Six Flags White Water Atlanta) ("SFOG", and together with SFOT, the "Partnership Parks") as subsidiaries in our consolidated financial statements as we have determined that we have the power to direct the activities of those entities that most significantly impact the entities’ economic performance and we have the obligation to absorb losses and receive benefits from the entities that can be potentially significant to these entities. The equity interests owned by non-affiliated parties in the Partnership Parks are reflected in the accompanying consolidated balance sheets as redeemable noncontrolling interests. The portion of earnings or loss attributable to non-affiliated parties in the Partnership Parks is reflected as net income attributable to noncontrolling interests in the accompanying consolidated statements of operations. See Note 6 for further discussion. Intercompany transactions and balances have been eliminated in consolidation. b. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our consolidated financial statements and accompanying notes. Actual results could differ from those estimates. We evaluate our estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which we believe to be reasonable under the circumstances. We adjust such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in these estimates resulting from continuing changes in the economic environment will be reflected in the financial statements in future periods. c. Fair Value Measurement Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement Fair Value Measurement ● Level 1: quoted prices in active markets for identical assets; ● Level 2: inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the instrument; and ● Level 3: inputs to the valuation methodology are unobservable for the asset or liability. The fair value of a financial instrument is the amount at which the instrument could be exchanged in a current transaction between willing parties. We use a market approach for our recurring fair value measurements, and we endeavor to use the best information available. Accordingly, valuation techniques that maximize the use of observable impacts are favored. We present the estimated fair values and classifications of our financial instruments in accordance with FASB Accounting Standards Consideration ("ASC") Topic 820, Fair Value Measurement. The following methods and assumptions were used to estimate the fair value of each class of financial instruments: ● The carrying values of cash and cash equivalents, accounts receivable, notes receivable, accounts payable and accrued liabilities approximate fair value because of the short maturity of these instruments. ● The measurement of the fair value of long-term debt is based on market prices that generally are observable for similar liabilities at commonly quoted intervals and is considered a Level 2 fair value measurement. Refer to Note 8 for additional information. ● The measurement of the fair value of derivative assets and liabilities is based on market prices that generally are observable for similar assets and liabilities at commonly quoted intervals and is considered a Level 2 fair value measurement. Derivative assets and liabilities that have maturity dates equal to or less than twelve months from the balance sheet date are included in prepaid expenses and other current assets and other accrued liabilities, respectively. Derivative assets and liabilities that have maturity dates greater than twelve months from the balance sheet date are included in deposits and other assets and other long-term liabilities, respectively. See Note 7 for additional information on our derivative instruments. d. Cash Equivalents Cash equivalents consists of short-term highly liquid investments with a remaining maturity as of the date of purchase of three months or less. For purposes of the consolidated statements of cash flows, we consider all highly liquid debt instruments with remaining maturities as of their date of purchase of three months or less to be cash equivalents. Cash equivalents were not significant as of December 31, 2020 and 2019. e. Inventories Inventories are stated at lower of weighted average cost or net realizable value and primarily consist of products purchased for resale, including merchandise, food and miscellaneous supplies. Products are removed from inventory at weighted average cost. We have recorded a $0.7 million and a $0.4 million allowance for slow moving inventory as of December 31, 2020 and 2019, respectively. f. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets include $21.6 million and $22.9 million of spare parts inventory for existing rides and attractions as of December 31, 2020 and 2019. These items are expensed as the repair or maintenance of rides and attractions occur. g. Advertising Costs Production costs of commercials and programming are charged to operations in the year first aired. The costs of other advertising, promotion, and marketing programs are charged to operations when incurred with the exception of direct-response advertising which is charged to the period it will benefit. As of December 31, 2020 and 2019, we had $1.6 million and $1.8 million in prepaid advertising, respectively. The amounts capitalized are included in prepaid expenses. Advertising and promotions expense was $19.6 million, $69.5 million and $68.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. h. Debt Issuance Costs We capitalize costs related to the issuance of debt. Debt issuance costs directly related to the Second Amended and Restated Revolving Loan are presented within other assets as debt issuance costs in our consolidated balance sheets. Debt issuance costs directly related to the Second Amended and Restated Term Loam B and our senior unsecured notes are presented within noncurrent liabilities as a reduction of long-term debt in our consolidated balance sheets. The amortization of such costs is recognized as interest expense using the interest method over the term of the respective debt issue. Amortization related to debt issuance costs was $6.5 million, $3.6 million and $4.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. See Note 8 for further discussion. i. Property and Equipment Property and equipment additions are recorded at cost and the carrying value is depreciated using the straight-line method over the estimated useful lives of the assets. Maintenance and repair costs that do not improve service potential or extend economic life are charged directly to expense as incurred, while betterments and renewals are generally capitalized as property and equipment. When an item is retired or otherwise disposed of, the cost and applicable accumulated depreciation are removed and the resulting gain or loss is recognized. See Note 4 for further detail of the components of our property and equipment. The estimated useful lives of the assets are as follows: ​ ​ ​ ​ Rides and attractions 5 - 25 years Land improvements ​ 10 - 15 years Buildings and improvements ​ Approximately 30 years Furniture and equipment ​ 5 - 10 years ​ j. Goodwill and Indefinite-Lived Intangible Assets Goodwill and intangible assets with indefinite useful lives are tested for impairment annually in the fourth quarter, or more frequently if events or circumstances indicate that the assets might be impaired. We identify our reporting unit and determine the carrying value of the reporting unit by assigning the assets and liabilities, including the existing goodwill and intangible assets, to the reporting unit. We then determine the fair value of the reporting unit and compare it to the carrying amount of the reporting unit. All of our parks are operated in a similar manner and have comparable characteristics in that they produce and distribute similar services and products using similar processes, have similar types of customers, are subject to similar regulations and exhibit similar economic characteristics. As such, we are a single reporting unit. For each year, the fair value of the single reporting unit exceeded our carrying amount (provided that, we have one reporting unit at the same level for which Holdings common stock is traded, we believe our market capitalization is the best indicator of our reporting unit’s fair value). We perform a qualitative analysis on indefinite-lived intangible assets to determine if it is more likely than not that the fair value of the intangible asset was less than its carrying amount as a basis for determining whether it was necessary to perform a quantitative impairment test. The fair value of indefinite-lived intangible assets is generally determined based on a discounted cash flow analysis. An impairment loss occurs to the extent that the carrying value exceeds the fair value. For goodwill, if the fair value of the reporting unit were to be less than the carrying amount, an impairment loss would be recognized to the extent that the carrying amount of the reporting unit exceeds its fair value. k. Valuation of Long-Lived Assets We review long-lived assets, including finite-lived intangible assets subject to amortization, for impairment upon the occurrence of events or changes in circumstances that would indicate that the carrying value of the asset or group of assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset or group of assets to the future net cash flows expected to be generated by the asset or group of assets. If such assets are not considered to be fully recoverable, any impairment to be recognized is measured by the amount by which the carrying amount of the asset or group of assets exceeds its respective fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell. l. Revenue Recognition We account for revenue from contracts with customers based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We recognize revenue upon admission into our parks, provision of our services, or when products are delivered to our guests. Revenues are presented in the accompanying consolidated statements of operations net of sales taxes collected from our guests that are remitted or payable to government taxing authorities. For season passes, memberships in the initial twelve-month term and other multi-use admissions, we estimate a redemption rate based on historical experience and other factors and assumptions we believe to be customary and reasonable and recognize a pro-rata portion of the revenue as the guests visit our parks. Amounts owed or received for multi-use admissions in excess of redemptions are recognized in deferred revenue. In contrast to our season pass and other multi-use offerings (such as our all season dining pass program, which enables season passholders and members to eat meals and snacks any day they visit the park for one upfront payment) that expire at the end of each operating season, the membership program continues on a month-to-month basis after the initial twelve-month membership term and can be canceled any time after the initial term pursuant to the terms of the membership program. Guests enrolled in the membership program can visit our parks an unlimited number of times whenever the parks are open as long as the guest remains enrolled in the membership program. We review the estimated redemption rate on an ongoing basis and revise it as necessary throughout the year, including impact of changes to our season pass and memberships described above. For any bundled products with multiple performance obligations, revenue is allocated using the retail price of each distinct performance obligation and products that are not sold on a stand-alone basis are treated as residual. ​ In connection with the temporary closure of our parks due to COVID-19, we added one ​ As of December 31, 2020, deferred revenue was primarily comprised of (i) unredeemed season pass and all-season dining pass revenue, (ii) unredeemed portions of the membership program and member dining program that will be recognized in 2021, and (iii) pre-sold single-day admissions revenue for the 2020 operating season which now expire at the end of the 2021 season. ​ Certain contracts with customers, primarily memberships, may include bundled products with multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the observable retail prices charged to customers and use residual for any products not sold on a stand-alone basis. We generally expense (i) sales commissions when incurred, and (ii) certain costs to obtain a contract where the amortization period would have been one year or less. These costs are recognized in "Selling, general and administrative expenses." We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less or (ii) contracts for which we recognize revenue at the amount for which we have the right to invoice for services performed. For certain of our contracts that have an original expected length of one year or less, we use the practical expedient applicable to such contracts and do not consider the time value of money. We have entered into international agreements to assist a third party in the planning, design, development and operation of a Six Flags-branded park outside of North America. These agreements consist of a brand licensing agreement, project services agreement, and management services agreement. We treat these agreements as one contract because they were negotiated with a single commercial objective. We have identified three distinct promises within the agreement with the third-party partner as brand licensing, project services and management services. Each of these promises is its own performance obligation and distinct, as the third party could benefit from each service on its own with other readily available resources, and each service is separately identifiable from other services in the context of the contract. We recognize revenue under our international agreements over the relevant service period of each performance obligation based on its relative stand-alone selling price, as determined by our best estimate of selling price. We review the service period of each performance obligation on an ongoing basis and revise it as necessary throughout the year. Revisions to the relevant service periods of the performance obligations may result in revisions to revenue in future periods and are recognized in the period in which the change is identified. m. Accounts Receivable, Net Accounts receivable are reported at net realizable value and consist primarily of amounts due from guests for the sale of group outings and multi-use admission products, including the membership program. We are not exposed to a significant concentration of credit risk, however, based on the age of the receivables, our historical experience and other factors and assumptions we believe to be customary and reasonable, we do record an allowance for doubtful accounts. As of December 31, 2020 and 2019, we have recorded an allowance for doubtful accounts of $3.1 million and $8.3 million, respectively. The allowance for doubtful accounts is primarily comprised of estimated defaults under our membership plans. n. Derivative Instruments and Hedging Activities We recognize all derivatives as either assets or liabilities in the consolidated balance sheet and measure those instruments at fair value. If certain conditions are met, a derivative may be specifically designated as a hedge for accounting purposes. The accounting for changes in the fair value of a derivative (e.g., gains and losses) depends on the intended use of the derivative and the resulting designation. We formally document all relationships between hedging instruments and hedged items, as well as our risk-management objective and our strategy for undertaking various hedge transactions. This process includes linking all derivatives that are designated as cash flow hedges to forecasted transactions. We also assess, both at the hedge’s inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows of hedged items. Change in the fair value of a derivative that is effective and that is designated and qualifies as a cash-flow hedge are recorded in other comprehensive (loss) income until operations are affected by the variability in cash flows of the designated hedged item, at which point they are reclassified to interest expense. Change in fair value of a derivative that is not designated as a hedge are recorded in other expense, net in the consolidated statements of operations on a current basis. In June 2019, we entered into three separate interest rate swap agreements with a notional amount of $300.0 million (collectively, the “June 2019 Swap Agreements”) to mitigate the risk of an increase in the LIBOR interest rate in effect on the Second Amended and Restated Term Loan B. In August 2019, we entered into two additional separate interest rate swap agreements with a notional amount of $400.0 million (collectively, the “August 2019 Swap Agreements”) to mitigate the risk of an increase in the LIBOR interest rate in effect on the Second Amended and Restated Term Loan B. In March 2020, we executed a strategy commonly known as a “blend and extend” on $100.0 million of the June 2019 Swap Agreements (the “Modified June 2019 Swap Agreement”) that extended the length of one of the June 2019 Swap Agreements through April 2026. We extended the existing pay-fixed swap rate over a longer period than its original term at a lower interest rate, while maintaining the same overall value of the swap. The remaining $200.0 million of the June 2019 Swap Agreements (the “Unmodified June 2019 Swap Agreements”) did not change. Upon execution, we designated and documented the Modified June 2019 Swap Agreement as a cash flow hedge. The Modified June 2019 Swap Agreement serves as an economic hedge and provides protection against rising interest rates. On April 22, 2020, we repaid $315.0 million of the Second Amended and Restated Term Loan B. In conjunction, the June 2019 Swap Agreements and the Modified June 2019 Swap Agreement were de-designated, since the hedged items were no longer probable to occur due to the repayment of the debt. In April 2020, we entered into $300.0 million of notional amount counter-agreements (the “April 2020 Counter-agreements”) designed to economically offset the impact of the de-designated swap agreements. See Note 7 for a further discussion. o. Commitments and Contingencies We are involved in various lawsuits and claims that arise in the normal course of business. Amounts associated with lawsuits or claims are reserved for matters in which it is believed that losses are probable and can be reasonably estimated. In addition to matters in which it is believed that losses are probable, disclosure is also provided for matters in which the likelihood of an unfavorable outcome is at least reasonably possible but for which a reasonable estimate of loss or range of loss is not possible. Legal fees are expensed as incurred. See Note 15 for further discussion. p. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, including net operating loss and other tax carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. We have a valuation allowance of $128.2 million and $130.6 million as of December 31, 2020 and 2019, respectively, due to uncertainties related to our ability to utilize some of our deferred tax assets, primarily consisting of certain state net operating loss, foreign tax credits and other tax carryforwards, before they expire. The valuation allowance was based on our estimates of taxable income by jurisdiction in which we operate and the period over which our deferred tax assets were recoverable. For the foreseeable future, we project taxable income that will allow for the utilization of all of our federal net operating loss carryforwards. Our liability for income taxes is finalized as auditable tax years pass their respective statutes of limitations in the various jurisdictions in which we are subject to tax. However, these jurisdictions may audit prior years for which the statute of limitations is closed for the purpose of making an adjustment to our taxable income in a year for which the statute of limitations has not closed. Accordingly, taxing authorities of these jurisdictions may audit prior years of the group and its predecessors for the purpose of adjusting net operating loss carryforwards to years for which the statute of limitations has not closed. We classify interest and penalties attributable to income taxes as part of income tax expense. As of December 31, 2020 and 2019, we had no accrued interest and penalties liability. Because we do not permanently reinvest foreign earnings, United States deferred income taxes have been provided on unremitted foreign earnings to the extent that such foreign earnings are expected to be taxable upon repatriation. For global intangible low taxed income ("GILTI") under the Tax Cuts and Jobs Act, we have elected to account for GILTI as a component of tax expense in the period in which we are subject to the rules (the "period cost method"). See Note 11 for further discussion. q. (Loss) earnings Per Common Share Basic (loss) earnings per common share is computed by dividing net (loss) income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed by dividing net income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding during the period including the effect of all dilutive common stock equivalents using the treasury stock method. In periods for which there is a net loss, diluted loss per common share is equal to basic loss per common share, since the effect of including any common stock equivalents would be antidilutive. r. Stock-Based Compensation Pursuant to the Six Flags Entertainment Corporation Long-Term Incentive Plan (the "Long-Term Incentive Plan"), Holdings may grant stock options, stock appreciation rights, restricted stock, restricted stock units, unrestricted stock, deferred stock units, performance and cash-settled awards and dividend equivalents to select employees, officers, directors and consultants of Holdings and its affiliates. We recognize the fair value of each grant as compensation expense on a straight-line basis over the vesting period using the graded vesting terms of the respective grant. The fair value of stock option grants is estimated on the date of grant using the Black-Scholes option pricing valuation model. The fair value of stock, restricted stock units and restricted stock awards is the quoted market price of Holdings’ stock on the date of grant. See Note 10 for further discussion of stock-based compensation and related disclosures. s. Comprehensive (Loss) Income Comprehensive (loss) income consists of net (loss) income, changes in the foreign currency translation adjustment, changes in the fair value of derivatives that are designated as hedges and changes in the net actuarial gains (losses) and amortization of prior service costs on our defined benefit retirement plan. t. Redeemable Noncontrolling Interest We record the carrying amount of our redeemable noncontrolling interests at their fair value at the date of issuance. We recognize the changes in their redemption value immediately as they occur and adjust the carrying value of these redeemable noncontrolling interests to equal the redemption value at the end of each reporting period, if greater than the redeemable noncontrolling interest carrying value. This method would view the end of the reporting period as if it were also the redemption date for the redeemable noncontrolling interests. We conduct an annual review to determine if the fair value of the redeemable units is less than the redemption amount. If the fair value of the redeemable units is less than the redemption amount, there would be a charge to earnings per share allocable to common stockholders. The redemption amount at the end of each reporting period did not exceed the fair value of the redeemable units. u. Leases We or certain of our subsidiaries are a lessee in various noncancelable operating and finance (formerly “capital”) leases, primarily for operating rights to amusement parks, land, office space, warehouses, office equipment and machinery. We account for leases in accordance with FASB ASC 842, Leases For both our operating and finance leases, the lease liability is initially and subsequently measured at the present value of the unpaid lease payments at the lease commencement date. Key estimates and judgments include how we determine (i) the discount rate used to discount the unpaid lease payments to present value, (ii) the lease term and (iii) the lease payments. Topic 842 requires a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate ("IBR"). Generally, we cannot determine the interest rate implicit in the lease and therefore we use the IBR as a discount rate for our leases. The IBR reflects the rate of interest we would pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The lease term for all of our leases includes the noncancelable period of the lease plus any additional periods covered by an option to extend the lease that are reasonably certain to be executed by us. Lease payments included in the measurement of the lease liability comprise fixed payments owed over the lease term, variable lease payments that depend on an index or rate, and the exercise price of an option to purchase the underlying asset if it is reasonably certain that we will exercise the option. The ROU asset is initially measured at cost, which comprises the initial amount of lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred, less any lease incentives received. For our operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, and adjusted for any prepaid or accrued lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the term of the operating lease. Variable lease payments associated with our leases are recognized upon the occurrence of the event, activity, or circumstance in the lease agreement on which those payments are assessed. Variable lease payments for operating leases are presented as operating expense in our consolidated statements of operations in the same line item as expense arising from fixed lease payments. Property taxes and insurance paid on behalf of our lessors is included within variable lease payments. Operating lease ROU assets net of accumulated amortization are presented as "Right-of-use operating leases, net" on the consolidated balance sheets. The current portion of operating lease liabilities is presented as "Short-term operating lease liabilities" and the long-term portion is presented separately as "Long-term operating lease liabilities" on the consolidated balance sheets. Finance lease ROU assets are presented within “Property and equipment, at cost” and the related lease amortization within “Accumulated depreciation” on our consolidated balance sheets. The current portion of the finance lease liabilities is presented as “Short-term lease liabilities” and the long-term portion is presented separately as “Long-term lease liabilities” on our consolidated balance sheets. We have elected not to recognize ROU assets and lease liabilities for short-term leases that have a lease term of 12 months or less. We recognize the lease payments associated with short-term leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with short-term leases are recognized and presented in the same manner as for all other leases. The ROU assets for operating leases may be periodically reduced by impairment losses. We use the long-lived assets impairment guidance to determine whether an ROU asset is impaired and if so, the amount of the impairment loss to recognize. We monitor for events or changes in circumstances that require a reassessment of one of our leases. When a reassessment results in the remeasurement of a lease liability, an adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the amount of the adjustment that would result in a negative ROU asset balance is recorded in our consolidated statements of operations. v. Acquisition of Park Assets On May 22, 2018, we entered into an asset purchase agreement with Premier Parks, LLC and its affiliates to acquire the lease rights to operate five parks owned by EPR Properties, LLC (the "five new parks"). We completed the transaction on June 1, 2018. In connection with the purchase agreement, we entered into operating leases with EPR Properties, LLC, under which we are the tenant. The five new parks were previously operated by Premier Parks, LLC of Oklahoma City and its affiliates. These acquisitions expanded our portfolio of parks in North America to twenty-five at the time of acquisition. The financial results of the five new parks since the acquisition date are included in our consolidated statements of operations. Assets acquired and liabilities assumed, consisting primarily of working capital, are reflected in our consolidated financial statements. We paid $19.1 million in cash to Premier Parks, LLC for the five new parks, which reflects the $23.0 million purchase price, less net working capital and other adjustments. We recorded $29.4 million of goodwill in connection with the acquisition, which is attributable to the excess of the purchase price over the net working capital liabilities we assumed. w. Recently Adopted Accounting Pronouncements On January 1, 2020, we adopted Accounting Standards Update 2016-13, Measurement of Credit Losses on Financial Instruments In March 2020, FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting x. Recent Accounting Pronouncem

Revenue

Revenue	12 Months Ended
	Dec. 31, 2020
Revenue
Revenue	3. Revenue Revenue Recognition Revenues are recognized when control of the promised goods or services is transferred to our customers in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Sales and other taxes we collect concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense. The following tables present our revenues disaggregated by contract duration for the years ended December 31, 2020, 2019 and 2018, respectively. Long-term and short-term contracts consist of our contracts with customers with terms greater than one year and less than or equal to one year, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 28,627 ​ $ 2,431 ​ $ 20,762 ​ $ 51,820 Short-term contracts and other (a) ​ 174,019 ​ 123,875 ​ 6,861 ​ 304,755 Total revenues ​ $ 202,646 ​ $ 126,306 ​ $ 27,623 ​ $ 356,575 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 106,233 ​ $ 20,381 ​ $ 71,893 ​ $ 198,507 Short-term contracts and other (a) ​ 709,549 ​ 554,059 ​ 25,468 ​ 1,289,076 Total revenues ​ $ 815,782 ​ $ 574,440 ​ $ 97,361 ​ $ 1,487,583 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 115,612 ​ $ 25,383 ​ $ 71,589 ​ $ 212,584 Short-term contracts and other (a) ​ 694,452 ​ 528,144 ​ 28,527 ​ 1,251,123 Total revenues ​ $ 810,064 ​ $ 553,527 ​ $ 100,116 ​ $ 1,463,707 ​ (a) Other revenues primarily include sales of single-use tickets and short-term transactional sales for which we have the right to invoice. Long-term Contracts Our long-term contracts consist of season passes purchased by customers in the year preceding the operating season to which they relate, sponsorship contracts and international agreements with third parties. Due to the COVID-19 pandemic, we have extended all 2020 season passes through the 2021 season. Due to the extension of term on the 2020 season passes, all 2020 season passes have a length greater than one year and are thus considered long-term contracts. We earn season pass revenue when our customers purchase a season pass for a fixed fee, which entitles the customer to visit our parks, including certain waterparks, throughout the duration of the parks’ operating season. We earn sponsorship revenue from separately-priced contracts with third parties pursuant to which we sell and advertise the third party’s products within the parks in exchange for consideration. Advertisements may include, but are not limited to, banners, signs, radio ads, association with certain events, sponsorship of rides within our parks and retail promotions. We earn international agreements revenue pursuant to arrangements in which we assist in the development and management of Six Flags-branded parks outside of North America. Within our international agreements, we have identified three distinct performance obligations as brand licensing, project services and management services. We do not consider revenue recognized for the performance obligations related to our international agreements to be significant, neither individually nor in the aggregate, to any period presented. See Note 1 for additional information on our accounting for performance obligations under these contracts. The transaction price for our long-term contracts is explicitly stated within the contracts. Our sponsorship contracts and international agreements may include estimated variable consideration such as penalties for delay in performance of contract terms, and certain volume-based discounts and rebates. We do not believe there will be significant changes to our estimates of variable consideration. Our brand licensing and management services performance agreements include royalty payments and management fees, respectively, based on gross sales from Six Flags-branded parks once opened. We have elected to apply the sales-based royalty exemption to the brand licensing performance obligation, and accordingly, do not estimate revenue attributable to the gross sales-based royalty. We have also elected to apply the direct allocation exemption to the management services performance obligation, and accordingly, do not estimate revenue attributable to the gross sales-based management fee. We recognize season pass revenue in "Park admissions" over the estimated redemption rate, as we believe this appropriately depicts the transfer of service to our customers. We estimate the redemption rate based on historical experience and other factors and assumptions that we believe to be customary and reasonable. We review the estimated redemption rate regularly, on an ongoing basis, and revise it as necessary throughout the year. Amounts received for multi-use admissions in excess of redemptions are recognized in "Deferred revenue." We recognize sponsorship and international agreements revenue over the term of the agreements using the passage of time as a measure of complete satisfaction of the performance obligations in "Sponsorship, international agreements and accommodations." Amounts received for unsatisfied sponsorship and international agreements performance obligations are recognized in "Deferred revenue." At January 1, 2019, $100.8 million of unearned revenue associated with outstanding long-term contracts was reported in “Deferred revenue,” and $161.0 million was recognized as revenue for long-term contracts during the year ended December 31, 2019. As of December 31, 2019, the total unearned amount of revenue for remaining long-term contract performance obligations was $85.1 million. At January 1, 2020, $85.1 million of unearned revenue associated with outstanding long-term contracts was reported in "Deferred revenue," and $51.2 million was recognized as revenue for long-term contracts during the year ended December 31, 2020. As of December 31, 2020, the total unearned amount of revenue for remaining long-term contract performance obligations was $77.6 million. As of December 31, 2020, we expect to recognize estimated revenue for partially or wholly unsatisfied performance obligations on long-term contracts of approximately $96.8 million in 2021 2022 2023 Short-term Contracts and Other Our short-term contracts consist primarily of season passes and memberships with customers, certain sponsorship contracts and international agreements with third parties. We earn revenue from a customer’s purchase of our season pass and membership products, which entitles the customer to visit our parks, including certain waterparks, throughout the duration of the parks’ operating season for a fixed fee. Some membership products include other benefits and discounts for our guests during their visits. We earn sponsorship and international agreements revenue from contracts with third parties, pursuant to which we sell and advertise the third party’s products within our parks on a short-term basis that generally coincides with our annual operating season, and pursuant to certain activities in connection with our international agreements. The transaction price for our short-term contracts is explicitly stated within the contracts. We generally recognize revenue from short-term contracts over the passage of time, with the exception of season pass and membership revenues. We estimate the redemption rate based on historical experience and other factors and assumptions we believe to be customary and reasonable. We review the estimated redemption rate regularly and on an ongoing basis and revise it as necessary throughout the year. Amounts received for multi-use admissions in excess of redemptions are recognized in "Deferred revenue." Other revenues consist primarily of revenues from single-use tickets for entrance to our parks, in-park services (such as the sale of food and beverages, merchandise, games and attractions, standalone parking sales and other services inside our parks), accommodations revenue, and other miscellaneous products and services. Due to the short-term transactional nature of such purchases, we apply the practical expedient to recognize revenue for single-use ticket sales, in-park services, accommodations, and other miscellaneous services and goods for which we have the right to invoice. ​ Arrangements with Multiple Performance Obligations Certain contracts with customers, primarily memberships, may include bundled products with multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the observable retail prices charged to customers and use residual for any products not sold on a stand-alone basis. We generally expense (i) sales commissions when incurred, and (ii) certain costs to obtain a contract where the amortization period would have been one year or less. These costs are recognized in "Selling, general and administrative expenses." We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less or (ii) contracts for which we recognize revenue at the amount for which we have the right to invoice for services performed. For certain of our contracts that have an original expected length of one year or less, we use the practical expedient applicable to such contracts and do not consider the time value of money. Practical Expedients and Exemptions We generally expense (i) sales commissions when incurred, and (ii) certain costs to obtain a contract where the amortization period would have been one year or less. These costs are recorded within Selling, general and administrative expenses. We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount for which we have the right to invoice for services performed. For certain of our contracts that have an original expected length of one year or less, we use the practical expedient applicable to such contracts and do not consider the time value of money.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property and Equipment
Property and Equipment	4. Property and Equipment As of December 31, 2020, and 2019, property and equipment was classified as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Land ​ $ 219,453 ​ $ 221,616 Land improvements ​ 274,089 ​ 264,417 Buildings and improvements ​ 324,943 ​ 318,960 Rides and attractions ​ 1,207,029 ​ 1,213,543 Equipment and other ​ 383,176 ​ 326,747 Property and equipment, at cost ​ 2,408,690 ​ 2,345,283 Accumulated depreciation ​ (1,157,403) ​ (1,061,287) Property and equipment, net ​ $ 1,251,287 ​ $ 1,283,996 ​

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets
Goodwill and Intangible Assets	5. Goodwill and Intangible Assets For the year ended December 31, 2020, we performed a qualitative analysis of our goodwill and indefinite-lived intangible assets and noted no indicators of impairment. Through that analysis, we determined that it is not likely that the carrying value of goodwill and indefinite-lived intangible assets exceeded their respective fair values. As of each of December 31, 2020 and 2019, the carrying amount of goodwill was $659.6 million. As of December 31, 2020 and 2019, intangible assets, net consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 ​ Weighted-Average ​ ​ ​ ​ ​ ​ ​ Remaining ​ ​ ​ ​ ​ ​ ​ Amortization Period ​ Gross ​ Accumulated ​ Net (Amounts in thousands, except years) (Years) ​ Carrying Value ​ Amortization ​ Carrying Value Indefinite-lived intangible assets: ​ ​ ​ ​ ​ Trade names, trademarks and other ​ $ 344,075 ​ $ — ​ $ 344,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finite-lived intangible assets: ​ ​ ​ Third party licensing rights 5.5 ​ 361 ​ (238) ​ 123 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total intangible assets, net ​ $ 344,436 ​ $ (238) ​ $ 344,198 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Weighted-Average ​ ​ ​ ​ ​ ​ ​ Remaining ​ ​ ​ ​ ​ ​ ​ Amortization Period ​ Gross ​ Accumulated ​ Net (Amounts in thousands, except years) (Years) ​ Carrying Value ​ Amortization ​ Carrying Value Indefinite-lived intangible assets: ​ ​ ​ ​ ​ Trade names, trademarks and other ​ $ 344,075 ​ $ — ​ $ 344,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finite-lived intangible assets: ​ ​ ​ Third party licensing rights 0.5 ​ 24,361 ​ (23,224) ​ 1,137 Other — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total intangible assets, net ​ $ 368,436 ​ $ (23,224) ​ $ 345,212 ​ Amortization expense related to finite-lived intangible assets totaled $1.0 million during the year ended December 31, 2020 and $2.4 million for the years ended December 31, 2019 and 2018. During the year we wrote off a fully amortized finite life intangible totaling $24.0 million. We expect that amortization expense on our existing intangible assets subject to amortization for the succeeding five years and thereafter will approximate the following: ​ ​ ​ ​ ​ (Amounts in thousands) ​ For the year ending December 31: ​ ​ 2021 ​ $ 22 2022 ​ ​ 22 2023 ​ ​ 22 2024 ​ ​ 22 2025 ​ ​ 22 2026 and thereafter ​ ​ 13 ​ ​ $ 123 ​

Noncontrolling Interests, Partn

Noncontrolling Interests, Partnerships and Joint Ventures	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interests, Partnerships and Joint Ventures
Noncontrolling Interests, Partnerships and Joint Ventures	6. Noncontrolling Interests, Partnerships and Joint Ventures Redeemable Noncontrolling Interests Redeemable noncontrolling interests represent the non-affiliated parties’ share of the assets of the Partnership Parks that are less than wholly-owned: SFOT, SFOG and Six Flags White Water Atlanta, which is owned by the partnership that owns SFOG. The following table presents a rollforward of redeemable noncontrolling interests in the Partnership Parks: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) SFOT SFOG Total Balance at December 31, 2018 ​ $ 243,756 ​ $ 281,515 ​ $ 525,271 Fresh start accounting fair market value adjustment for purchased units ​ ​ (45) ​ ​ — ​ ​ (45) Purchases of redeemable units ​ ​ (217) ​ ​ — ​ ​ (217) Change in redemption value of partnership units ​ ​ 3,250 ​ ​ 999 ​ ​ 4,249 Net income attributable to noncontrolling interests ​ ​ 20,452 ​ ​ 20,301 ​ ​ 40,753 Distributions to noncontrolling interests ​ ​ (20,452) ​ ​ (20,301) ​ ​ (40,753) Balance at December 31, 2019 ​ ​ 246,744 ​ ​ 282,514 ​ ​ 529,258 Fresh start accounting fair market value adjustment for purchased units ​ ​ (720) ​ ​ (204) ​ ​ (924) Purchases of redeemable units ​ ​ (3,440) ​ ​ (1,536) ​ ​ (4,976) Change in redemption value of partnership units ​ ​ 11 ​ ​ 7 ​ ​ 18 Net income attributable to noncontrolling interests ​ ​ 20,634 ​ ​ 20,654 ​ ​ 41,288 Distributions to noncontrolling interests ​ ​ (20,634) ​ ​ (20,654) ​ ​ (41,288) Balance at December 31, 2020 ​ $ 242,595 ​ $ 280,781 ​ $ 523,376 ​ See Note 15 for a description of the partnership arrangements applicable to the Partnership Parks, the accounts of which are included in the accompanying consolidated financial statements. As of December 31, 2020, the redemption value of the noncontrolling partnership units in SFOT and SFOG equaled the carrying values.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2020
Derivative Financial Instruments
Derivative Financial Instruments	7. Derivative Financial Instruments In June 2019, we entered into the June 2019 Swap Agreements with an aggregate notional amount of $300.0 million to mitigate the risk of an increase in the LIBOR interest rate on the Second Amended and Restated Term Loan B. The term of the June 2019 Swap Agreements began in June 2019 and expires in June 2023. Upon execution, we designated and documented the June 2019 Swap Agreements as cash flow hedges. The June 2019 Swap Agreements serve as economic hedges and provide protection against rising interest rates. In August 2019, we entered into the August 2019 Swap Agreements with an aggregate notional amount of $400.0 million to mitigate the risk of an increase in the LIBOR interest rate in effect on the Second Amended and Restated Term Loan B. The term of the August 2019 Swap Agreements began in August 2019 and expires in August 2024. Upon execution, we designated and documented the August 2019 Swap Agreements as cash flow hedges. The August 2019 Swap Agreements serve as economic hedges and provide protection against rising interest rates. In March 2020, we executed a strategy commonly known as a “blend and extend” on $100.0 million of the June 2019 Swap Agreements that extended the length of one of the June 2019 Swap Agreements through April 2026. We extended the existing pay-fixed swap rate over a longer period than its original term at a lower interest rate, while maintaining the same overall value of the swap. The remaining $200.0 million of the June 2019 Swap Agreements did not change. On April 22, 2020, we repaid $315.0 million of the Second Amended and Restated Term Loan B. In conjunction, the June 2019 Swap Agreements and the Modified June 2019 Swap Agreement were de-designated, since the hedged interest was no longer probable of occurring due to the repayment of the debt. As a result, $14.9 million was reclassified from accumulated other comprehensive loss to interest expense in the consolidated statement of operations. Consistent with company policy, we hold and issue derivative instruments for risk management purposes only and do not utilize derivative instruments for trading or speculative purposes. Accordingly, in April 2020 we entered into $300.0 million of notional amount counter-agreements (the “April 2020 Counter-agreements”) designed to economically offset the impact of the de-designated swap agreements. By utilizing a derivative instrument to hedge our exposure to LIBOR rate changes, we are exposed to credit risk and market risk. Credit risk is the failure of the counterparty to perform under the terms of the derivative contract. To mitigate this risk, hedging instruments are placed with counterparties that we believe pose minimal credit risk. Market risk is the adverse effect on the value of a financial instrument that results from a change in interest rates, commodity prices or currency exchange rates. We manage the market risk associated with derivative instruments by establishing and monitoring parameters that limit the types and degree of market risk that we may undertake. We hold and issue derivative instruments for risk management purposes only and do not utilize derivatives for trading or speculative purposes. We record derivative instruments at fair value on our consolidated balance sheets. When in qualifying relationships, the gains and losses on cash flow designated derivatives are deferred in accumulated other comprehensive loss (“AOCL”) and are reclassified to interest expense when the forecasted transaction takes place. The fair value of derivatives that are not designated as hedging instruments are recorded directly to “interest expense”. Derivative assets and derivative liabilities that have maturity dates equal to or less than twelve months from the balance sheet date are included in prepaid expenses and other current assets and other accrued liabilities, respectively. Derivative assets and derivative liabilities that have maturity dates greater than twelve months from the balance sheet date are included in deposits and other assets and other long-term liabilities, respectively. Our derivatives are measured on a recurring basis using Level 2 inputs and the income approach. The fair value measurements of our derivatives are based on quoted prices and other inputs that are observable. Derivative assets recorded at fair value in our consolidated balance sheets as of December 31, 2020 and 2019, respectively, consisted of the following: ​ ​ ​ ​ ​ ​ ​ Derivative Assets (Amounts in thousands) December 31, 2020 December 31, 2019 Derivatives Designated as Cash Flow Hedges ​ ​ ​ ​ ​ Interest Rate Swap Agreements — Current $ — $ 485 Interest Rate Swap Agreements — Noncurrent ​ — ​ ​ 1,440 Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ Interest Rate Swap Agreements - Current 877 ​ — Interest Rate Swap Agreements - Noncurrent ​ 585 ​ ​ — ​ $ 1,462 $ 1,925 ​ Derivative liabilities recorded at fair value in our consolidated balance sheets as of December 31, 2020 and December 31, 2019, respectively, consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivative Liabilities (Amounts in thousands) ​ December 31, 2020 December 31, 2019 Derivatives Designated as Cash Flow Hedges ​ ​ ​ ​ ​ ​ Interest Rate Swap Agreements — Current ​ $ (5,251) $ (788) Interest Rate Swap Agreements — Noncurrent ​ ​ (11,633) ​ ​ (2,667) Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ Interest Rate Swap Agreements - Current ​ (4,875) ​ — Interest Rate Swap Agreements - Noncurrent ​ ​ (9,032) ​ ​ — ​ ​ $ (30,791) $ (3,455) ​ Losses before taxes on derivatives not designated as a cash flow hedge of $0.6 million were presented in “Interest expense” in the consolidated statement of operations for the year ended December 31, 2020. ​ Gains and losses before taxes on derivatives designated as hedging instruments were presented in “Interest expense” in the consolidated statement of operations for the years ended December 31, 2020, 2019 and 2018 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss ​ Loss Reclassified from ​ ​ Recognized in AOCL ​ AOCL into Operations (Amounts in thousands) 2020 2019 2018 2020 2019 2018 Interest Rate Swap Agreements ​ $ (33,902) ​ $ (484) $ — $ (3,685) ​ $ 1,046 $ — Total $ (33,902) ​ $ (484) $ — $ (3,685) ​ $ 1,046 $ — ​ As of December 31, 2020, we expect to reclassify net losses of $5.3 million, currently recorded in AOCL, into “Interest expense, net” within the next twelve months. However, the actual amount reclassified could vary due to future changes in the fair value of these derivatives. ​ During the year ended December 31, 2020, we recognized in AOCL a loss of $33.9 million related to our swap agreements. This loss was caused by a decrease in both current interest rates, the interest rate forward curve and the expectation of future payment by us to our hedging counterparties based on current assumptions of the market. Upon de-designation of the June 2019 Swap Agreements and the Modified June 2019 Swap Agreement, we reclassified $14.9 million from accumulated other comprehensive loss to interest expense in the consolidated statement of operations.

Long-Term Indebtedness

Long-Term Indebtedness	12 Months Ended
	Dec. 31, 2020
Long-Term Indebtedness
Long-Term Indebtedness	8. Long-Term Indebtedness Credit Facility As part of our ongoing operations, we periodically refinance our existing credit facility. As of December 31, 2020, our credit facility consisted of a $481.0 million revolving credit loan facility (the “Second Amended and Restated Revolving Loan”) and a $479.0 million Tranche B Term Loan facility (the “Second Amended and Restated Term Loan B”) pursuant to the amended and restated credit facility that we entered into in 2019 (the “Second Amended and Restated Credit Facility”). Our prior credit facility (as previously amended as described below, the “2015 Credit Facility”) consisted of a $250.0 million revolving credit loan facility (the “2015 Revolving Loan”) and a $700.0 million Tranche B Term Loan (the “2015 Term Loan B”) and was amended and restated in conjunction with the Second Amended and Restated Credit Facility. On April 17, 2019, we amended and restated the 2015 Credit Facility (as previously amended). The Second Amended and Restated Credit Facility was comprised of the $350.0 million Second Amended and Restated Revolving Loan and the $800.0 million Second Amended and Restated Term Loan B. In connection with entering into the Second Amended and Restated Credit Facility, we repaid the amounts outstanding on the 2015 Revolving Loan and the outstanding 2015 Term Loan B and we recognized a loss on debt extinguishment of $6.2 million. The remaining proceeds from the Second Amended and Restated Credit Facility were used for general corporate purposes, including payment of refinancing fees. We capitalized $8.9 million of debt issuance costs directly associated with the issuance of the Second Amended and Restated Credit Facility. On October 18, 2019, we entered into an amendment to the Second Amended and Restated Credit Facility, which reduced the overall borrowing rate on the Second Amended and Restated Term Loan B by 25 On April 8, 2020, certain of our revolving credit lenders agreed to provide an incremental $131.0 million of revolving credit commitments to the Second Amended and Restated Revolving Loan, increasing the facility from $350.0 million to $481.0 million. On April 15, 2020, we received sufficient consents from the continuing lenders under the Second Amended and Restated Credit Facility (the “Credit Agreement Amendment”) substantially concurrently with the closing of the $725 million 2025 Notes discussed below to, among other things, (i) permit the issuance of the 2025 Notes, including specifically, permitting the 2025 Notes to mature inside the Second Amended and Restated Term Loan B, (ii) suspend the testing of the senior secured leverage ratio financial maintenance covenant in the Second Amended and Restated Credit Facility through the end of 2020, (iii) re-establish the financial maintenance covenant thereafter (provided that for the first, second, and third quarters in 2021 that such covenant is tested, we will be permitted to use the quarterly Borrower Consolidated Adjusted EBITDA (as defined in the Second Amended and Restated Credit Facility) from the second, third and fourth quarters of 2019 in lieu of the actual Borrower Consolidated Adjusted EBITDA for the corresponding quarters of 2020) and (iv) add a minimum liquidity covenant that will apply from the date of the Credit Agreement Amendment through December 31, 2021. The Credit Agreement Amendment became effective on April 22, 2020, after giving effect to the repayment of a portion of the Second Amended and Restated Term Loan B with a portion of the proceeds from the 2025 Notes. On April 22, 2020, SFTP completed the private sale of $725.0 million in aggregate principal amount of 7.00% senior secured notes due 2025 (discussed below). The net proceeds from this offering were used to repay the outstanding balance of the Second Amended and Restated Revolving Loan and $315.0 million of the Second Amended and Restated Term Loan B and for general corporate and working capital purposes, including expenses relating to the offering. We recognized a loss on debt extinguishment of $5.1 million related to the transaction. On August 26, 2020, we entered into an amendment to the Second Amended and Restated Credit Facility which, among other things, (i) extended the previously effectuated suspension of the senior secured leverage ratio financial maintenance covenant in the Second Amended and Restated Credit Facility through the end of 2021, (ii) re-established the senior secured leverage ratio financial maintenance covenant thereafter (provided that for each quarter in 2022 (other than the fourth quarter) that the financial maintenance covenant is tested, SFTP will be permitted to use its quarterly Borrower Consolidated Adjusted EBITDA (as defined in the credit agreement governing the Second Amended and Restated Credit Facility) from the second, third, and fourth quarters of 2019 in lieu of the actual Borrower Consolidated Adjusted EBITDA for the corresponding quarters of 2021), (iii) reduced the commitment fee on the revolving credit facility, and (iv) extended the minimum liquidity covenant that will apply through December 31, 2022. The extension of the modifications to the financial covenant and other provisions in the Second Amended and Restated Credit Facility pursuant to this amendment will be in effect from the date of the amendment until the earlier of the delivery of the compliance certificate for the fourth quarter of 2022 and the date on which SFTP, in its sole discretion, elects to calculate its compliance with the financial maintenance covenant by using its actual Borrower Consolidated Adjusted EBITDA instead of the 2019 figures as outlined above. In addition, all of SFTP’s existing incremental revolving credit lenders agreed to extend the incremental $131 million revolving credit commitments to the Second Amended and Restated Revolving Loan by one year to December 31, 2022. As of December 31, 2020 and 2019, no amounts were outstanding under the Second Amended and Restated Revolving Loan (excluding amounts reserved for letters of credit in the amount of $21.0 million and $20.8 million, respectively). Interest on the Second Amended and Restated Revolving Loan accrues at an annual rate of LIBOR plus an applicable margin with an unused commitment fee based on our senior secured leverage ratio. As of December 31, 2020, the Second Amended and Restated Revolving Loan unused commitment fee was 0.30%. The principal amount of the Second Amended and Restated Revolving Loan is due and payable on April 17, 2024. As of December 31, 2020 and 2019, $479.0 million and $796.0 million, respectively, was outstanding under the Second Amended and Restated Term Loan B. Interest on the Second Amended and Restated Term Loan B accrues at an annual rate of LIBOR plus an applicable margin, based on our consolidated leverage ratio. In June 2019, we entered into the June 2019 Swap Agreements to mitigate the risk of an increase in the LIBOR interest rate in effect on the Second Amended and Restated Term Loan B. In August 2019, we entered into the August 2019 Swap Agreements to further mitigate the risk of an increase in the LIBOR interest rate in effect on the Second Amended and Restated Term Loan B. See Note 7 for further discussion of interest rate swaps. As of December 31, 2020 and 2019, the applicable interest rate on the Second Amended and Restated Term Loan B was 3.01% and 3.48%, respectively. All remaining outstanding principal of the Second Amended and Restated Term Loan B is due and payable on April 17, 2026. Amounts outstanding under the Second Amended and Restated Credit Facility are guaranteed by Holdings, Six Flags Operations Inc. ("SFO") and certain of the domestic subsidiaries of SFTP (collectively, the "Loan Parties"). The Second Amended and Restated Credit Facility is secured by a first priority security interest in substantially all of the assets of the Loan Parties. The Second Amended and Restated Credit Facility agreement contains certain representations, warranties, affirmative covenants and financial covenants (specifically, a maximum senior secured net leverage maintenance covenant). In addition, the Second Amended and Restated Credit Facility agreement contains restrictive covenants that, subject to certain exceptions, limit or restrict, among other things, the incurrence of indebtedness and liens, fundamental changes, restricted payments, capital expenditures, investments, prepayments of certain indebtedness, transactions with affiliates, changes in fiscal periods, modifications of certain documents, activities of the Company and SFO and hedging agreements, subject, in each case, to certain carve-outs. 2024 Notes, 2025 Notes and 2027 Notes On June 16, 2016, Holdings issued $300.0 million of 4.875% senior unsecured notes due July 31, 2024 (the "2024 Notes"). We capitalized $4.7 million of debt issuance costs directly associated with the issuance of the 2024 Notes. We used approximately $150.0 million of the proceeds from the issuance of the 2024 Notes to reduce our borrowings under the 2015 Term Loan B. We used the remaining net proceeds of the sale of the 2024 Notes for general corporate and working capital purposes, which primarily included repurchases of our common stock. On April 13, 2017, Holdings issued an additional $700.0 million of 4.875% Senior Notes due July 31, 2024 (the "2024 Notes Add-on"). We capitalized $3.9 million of debt issuance costs directly associated with the issuance of the 2024 Notes Add-on. Interest payments of $24.4 million for the 2024 Notes and the 2024 Notes Add-on are due semi-annually on January 31 and July 31 of each year, with the exception of the first payment for the 2024 Notes on January 31, 2017, which was $9.1 million. On April 13, 2017, Holdings issued $500.0 million of 5.50% Senior Notes due April 15, 2027 (the "2027 Notes"). We capitalized $2.6 million of debt issuance costs directly associated with the issuance of the 2027 Notes. During March of 2020, we prepaid $50.5 million of the outstanding 2024 Notes principal, reducing the outstanding amount to $949.5 million. We recognized a loss on debt extinguishment of $1.0 million. Interest payments of $23.1 million for the 2024 Notes and the 2024 Notes Add-on are due semi-annually on January 31 and July 31 of each year. On April 22, 2020, SFTP completed the private sale of $725.0 million in aggregate principal amount of 7.00% senior secured notes due 2025 (the “2025 Notes”). The net proceeds from this offering were used to repay the outstanding balance of the Second Amended and Restated Revolving Loan and $315.0 million of the Second Amended and Restated Term Loan B and for general corporate and working capital purposes, including expenses relating to the offering. In conjunction with the $315.0 million repayment of the Second Amended and Restated Term Loan B, certain of our hedging instruments that were entered into to mitigate the risk of an increase in the LIBOR interest rate and which are discussed in Note 7, Derivative Financial Instruments The 2024 Notes, the 2024 Notes Add-on, 2025 Notes and the 2027 Notes are guaranteed by the Loan Parties. The 2024 Notes, the 2024 Notes Add-on, 2025 Notes and the 2027 Notes contain restrictive covenants that, subject to certain exceptions, limit or restrict, among other things, the ability of the Loan Parties to incur additional indebtedness, create liens, engage in mergers, consolidations and other fundamental changes, make investments, engage in transactions with affiliates, pay dividends and repurchase capital stock. The 2024 Notes, the 2024 Notes Add-on, 2025 Notes and the 2027 Notes contain certain events of default, including payment defaults, breaches of covenants and representations, cross defaults to other material indebtedness, judgment, and changes of control and bankruptcy events of default. Total Indebtedness Summary As of December 31, 2020 and 2019, total debt consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of (Amounts in thousands) December 31, 2020 December 31, 2019 Second Amended and Restated Term Loan B $ 479,000 $ 796,000 2024 Notes ​ 949,490 ​ 1,000,000 2025 Notes ​ ​ 725,000 ​ ​ — 2027 Notes ​ 500,000 ​ 500,000 Net discount ​ (4,357) ​ (6,535) Deferred financing costs ​ (26,492) ​ (14,581) Total debt ​ $ 2,622,641 ​ $ 2,274,884 Less current portion of long-term debt ​ — ​ (8,000) Total long-term debt ​ $ 2,622,641 ​ $ 2,266,884 ​ As of December 31, 2020, annual maturities of long-term debt, assuming no acceleration of maturities, were as follows: ​ ​ ​ ​ (Amounts in thousands) ​ For the year ending December 31: ​ ​ 2021 ​ ​ — 2022 ​ ​ — 2023 ​ ​ — 2024 ​ ​ 949,490 2025 ​ ​ 725,000 2026 and thereafter ​ ​ 979,000 ​ ​ $ 2,653,490 ​ Fair-Value of Long-Term Indebtedness As of December 31, 2020 and December 31, 2019, the fair value of our long-term debt was $2,693.3 million and $2,348.9 million, respectively. The measurement of the fair value of long-term debt is based on market prices that are generally observable for similar liabilities at commonly quoted intervals and is considered a Level 2 fair value measurement.

Selling, General and Administra

Selling, General and Administrative Expenses	12 Months Ended
	Dec. 31, 2020
Selling, General and Administrative Expenses
Selling, General and Administrative Expenses	9. Selling, General and Administrative Expenses Selling, general and administrative expenses comprised the following for the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Park ​ $ 80,027 ​ $ 131,619 ​ $ 129,335 Corporate ​ 67,268 ​ 67,575 ​ 2,833 Total selling, general and administrative expenses ​ $ 147,295 ​ $ 199,194 ​ $ 132,168 ​ Corporate, selling, general and administrative expense includes stock-based compensation of $19.5 million and $13.3 million for the years ended December 31, 2020 and 2019, respectively, and a reversal of stock-based compensation expense of $46.7 million for the year ended December 31, 2018.

Stock Benefit Plans

Stock Benefit Plans	12 Months Ended
	Dec. 31, 2020
Stock Benefit Plans
Stock Benefit Plans	10. Stock Benefit Plans Pursuant to the Long-Term Incentive Plan, Holdings may grant stock options, stock appreciation rights, restricted stock, restricted stock units, unrestricted stock, deferred stock units, performance and cash-settled awards and dividend equivalents to select employees, officers, directors and consultants of Holdings and its affiliates. In May 2017, our stockholders approved amendments to the Long-Term Incentive Plan that increased the number of shares available for issuance under the Long-Term Incentive Plan by 4,000,000 shares. During the years ended December 31, 2020, 2019 and 2018 we recognized stock-based compensation expense related to the Long-Term Incentive Plan, excluding amounts related to our 2017 Performance Award (as defined below), of $19.1 million, $13.0 million and $15.5 million, respectively. As of December 31, 2020, options to purchase approximately 4,797,000 shares of common stock of Holdings and approximately 1,581,000 shares of restricted stock or restricted stock units were outstanding under the Long-Term Incentive Plan and approximately 4,375,000 shares were available for future grant. Stock Options Options granted under the Long-Term Incentive Plan are designated as either incentive stock options or non-qualified stock options. Options are generally granted with an exercise price equal to the fair market value of the common stock of Holdings on the date of grant. While certain stock options are subject to acceleration in connection with a change in control, options are generally cumulatively exercisable in four The estimated fair value of our options granted was calculated using the Black-Scholes option pricing valuation model. This model takes into account several factors and assumptions. The risk-free interest rate is based on the yield on United States Treasury zero-coupon issues with a remaining term equal to the expected term assumption at the time of grant. We have sufficient historical data to develop an expected term assumption and we calculated the expected term using a mid-point scenario with a one-year grant date filter to exclude grants for which vesting could not have yet occurred. Expected volatility is based three one The following weighted-average assumptions were utilized in the Black-Scholes model to value the stock options granted during the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 December 31, 2019 December 31, 2018 ​ ​ CEO Employees CEO Employees CEO Employees ​ Risk-free interest rate — ​ 1.60 % 1.59 % 1.42 % 2.52 % 2.67 % Expected life (in years) — 3.67 3.67 3.67 3.85 3.68 ​ Expected volatility — ​ 28.38 % 28.62 % 26.96 % 23.20 % 22.51 % Expected dividend yield — ​ 7.18 % 6.47 % 6.12 % 4.67 % 4.54 % ​ The following table summarizes stock option activity for the year ended December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Avg. ​ Weighted Avg. ​ ​ ​ ​ ​ ​ Exercise Price ​ Remaining ​ Aggregate ​ ​ ​ ​ Per Share ​ Contractual ​ Intrinsic Value (Amounts in thousands, expect per share and term data) ​ Shares ​ ($) ​ Term ​ ($) Balance at December 31, 2019 ​ 6,408 ​ $ 52.42 ​ ​ ​ Granted ​ 9 ​ $ 44.73 ​ ​ ​ Exercised ​ (127) ​ $ 17.64 ​ ​ ​ Canceled or exchanged ​ (1,061) ​ $ 53.50 ​ ​ ​ Forfeited ​ (432) ​ $ 59.85 ​ ​ ​ Expired ​ — ​ $ — ​ ​ ​ Balance at December 31, 2020 ​ 4,797 ​ $ 52.42 ​ 6.27 ​ $ 2,569 Vested and expected to vest at December 31, 2020 ​ 4,679 ​ $ 52.23 ​ 6.22 ​ $ 2,569 Options exercisable at December 31, 2020 ​ 2,993 ​ $ 49.30 ​ 5.08 ​ $ 2,569 ​ The following table presents the weighted average grant date fair value per share of the options granted, the total intrinsic value of options exercised, the total fair value of options that have vested, and the total cash received from the exercise of stock options during the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands, expect per share data) 2020 2019 2018 Weighted average grant date fair value per share of options granted ​ $ 4.85 ​ $ 6.38 ​ $ 8.01 Total intrinsic value of options exercised ​ $ 1,275 ​ $ 7,130 ​ $ 31,822 Total fair value of vested options ​ $ 7,369 ​ $ 10,253 ​ $ 8,446 Total cash received from the exercise of stock options ​ $ 2,235 ​ $ 17,495 ​ $ 41,658 ​ As of December 31, 2020, there was $5.6 million of unrecognized compensation expense related to option awards. The weighted-average period over which that cost is expected to be recognized is 2.43 years. Stock, Restricted Stock and Restricted Stock Units Stock, restricted stock and restricted stock units granted under the Long-Term Incentive Plan may be subject to transfer and other restrictions as determined by the compensation committee of Holdings’ Board of Directors. Generally, the unvested portion of restricted stock and restricted stock unit awards is forfeited upon termination of employment. The fair value of stock, restricted stock and restricted stock unit awards on the date of grant is expensed on a straight-line basis over the requisite service period of the graded vesting term as if the award was, in substance, multiple awards. During the year ended December 31, 2014, a performance award was established based on our goal to achieve Modified EBITDA of $600 million by 2017 (the "2017 Performance Award"). "Modified EBITDA” is defined as our consolidated income from continuing operations: excluding the cumulative effect of changes in accounting principles; discontinued operations gains or losses; income tax expense or benefit; restructure costs or recoveries; reorganization items (net); other income or expense; gain or loss on early extinguishment of debt; equity in income or loss of investees; interest expense (net); gain or loss on disposal of assets; gain or loss on the sale of investees; amortization; depreciation; stock-based compensation; and fresh start accounting valuation adjustments. We did not achieve the 2017 Performance Award goal and thus all previously recognized stock-based compensation associated with this award was reversed. During the year ended December 31, 2016, a performance award was established based on our goal to achieve Modified EBITDA of $750 million by 2020 (the "2020 Performance Award"). The aggregate payout under the performance award to key employees if the target was achieved in 2020 would have been 1,025,000 shares plus associated Dividend Equivalent Rights (“DERs”). The 2020 Performance Award was not achieved in 2020 and we believe that achievement in 2021, which provides for issuance of one-half of the target award, is highly unlikely and thus no expense has been recognized. The following table summarizes stock, restricted stock and restricted stock unit activity for the year ended December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average Grant ​ ​ ​ ​ ​ Date Fair Value ​ ​ ​ ​ ​ Per Share (Amounts in thousands, except per share amounts ​ Shares ​ ​ ($) Non-vested balance at December 31, 2019 ​ 62 ​ $ 48.29 Granted ​ 1,569 ​ $ 18.86 Vested ​ (50) ​ $ 40.19 Forfeited ​ (121) ​ $ 19.01 Canceled ​ — ​ $ — Non-vested balance at December 31, 2020 ​ 1,460 ​ $ 19.37 ​ The following table presents the weighted average grant date fair value per share of stock awards granted, the total grant date fair value of stock awards granted, and the total fair value of stock awards that have vested during the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands, expect per share data) 2020 2019 2018 Weighted average grant date fair value per share of stock awards granted ​ $ 18.86 ​ $ 48.29 ​ $ 63.80 Total grant date fair value of stock awards granted ​ $ 29,597 ​ $ 3,007 ​ $ 4,185 Total fair value of vested stock awards ​ $ 2,011 ​ $ 1,027 ​ $ 3,888 ​ There was $17.6 million of total unrecognized stock-based compensation expense related to stock, restricted stock and restricted stock units as of December 31, 2020, that is expected to be recognized over a weighted-average period of 2.36 years. Deferred Share Units Non-employee directors can elect to receive the value of their annual cash retainer as a deferred share unit award ("DSU") under the Long-Term Incentive Plan whereby the non-employee director is granted DSUs in an amount equal to such director’s annual cash retainer divided by the closing price of Holdings’ common stock on the date of the annual stockholders meeting. Each DSU represents Holdings’ obligation to issue one share of common stock. The shares are delivered approximately thirty days following the cessation of the non-employee director’s service as a director of Holdings’. DSUs generally vest consistent with the manner in which non-employee directors’ cash retainers are paid. The fair value of the DSUs on the date of grant is expensed on a straight line basis over the requisite service period. During each of the years ended December 31, 2020, 2019 and 2018, approximately 7,000 DSUs, 4,000 DSUs and 3,000 DSUs were granted, respectively, at a weighted-average grant date fair value of $31.43, $50.12 and $57.04 per DSU, respectively. The total grant date fair value of DSUs granted was $0.2 million for the years ended December 31, 2020, 2019 and 2018. As of December 31, 2020, there was no unrecognized compensation expense related to the outstanding DSUs. Dividend Equivalent Rights On February 8, 2012, Holdings’ Board of Directors granted DERs to holders of unvested stock options, at which time, approximately 10.0 million unvested stock options were outstanding. The DERs accrue dividends as of the record date of each of Holdings’ dividends that will be distributed to stock option holders upon the vesting of their stock option award. Holdings will distribute the accumulated accrued dividends pursuant to the DERs in either cash or shares of common stock. Generally, holders of stock options for fewer than 1,000 shares of stock will receive their accumulated accrued dividends in cash and holders of stock options for 1,000 shares of stock or greater will receive their accumulated accrued dividends in shares of common stock. In addition, Holdings’ Board of Directors granted similar DERs payable in shares of common stock if and when any shares are granted under the 2020 Performance Award. Holdings’ Board of Directors granted approximately 2.0 million and 1.5 million additional options to the majority of our full-time employees as well as DERs in connection with such options during the years ended December 31, 2019 and 2018, respectively. Exclusive of stock-based compensation recognized for the DER grants associated with the 2017 Performance Award discussed above, we recorded stock-based compensation for DER grants of $0.3 million, $5.0 million and $5.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. Employee Stock Purchase Plan The Six Flags Entertainment Corporation Employee Stock Purchase Plan (the "ESPP") allows eligible employees to purchase Holdings’ common stock at 90% of the lower of the market value of the common stock at the beginning or end of each successive six-month offering period. Amounts accumulated through participants’ payroll deductions ("purchase rights") are used to purchase shares of common stock at the end of each purchase period. No more than 2,000,000 shares of common stock of Holdings may be issued pursuant to the ESPP. Holdings’ common stock may be issued from authorized and unissued shares, treasury shares or shares purchased on the open market. As of December 31, 2020, we had 1,579,000 shares available for purchase pursuant to the ESPP. Stock-based compensation related to purchase rights is recognized based on the intrinsic value of each respective six-month ESPP offering period. As of December 31, 2020 and 2019, no purchase rights were outstanding under the ESPP. Stock-based compensation consisted of the following amounts for the years ended December 31, 2020, 2019 and 2018. We present separately the reversal of previously recorded stock-based compensation related to the 2017 Performance Award from our Long-Term Incentive Plan and Employee Stock Purchase Plan. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 ​ 2019 ​ 2018 Long-Term Incentive Plan ​ ​ ​ ​ ​ Options and other $ 19,078 ​ $ 13,037 ​ $ 15,543 Performance awards — ​ — ​ (62,512) Employee Stock Purchase Plan 452 ​ 237 ​ 285 Total Stock-Based Compensation $ 19,530 ​ $ 13,274 ​ $ (46,684) ​

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Taxes
Income Taxes	11. Income Taxes The following table summarizes the domestic and foreign components of our income (loss) before income taxes for the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Domestic ​ $ (487,594) ​ $ 297,752 ​ $ 383,875 Foreign ​ (35,464) ​ 14,008 ​ 27,983 (Loss) income before income taxes ​ $ (523,059) ​ $ 311,760 ​ $ 411,858 ​ The following table summarizes the components of income tax (benefit) expense for the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) Current Deferred Total 2020: ​ ​ ​ ​ ​ ​ U.S. federal ​ $ (3,530) ​ $ (99,976) ​ $ (103,506) Foreign ​ — ​ (7,642) ​ (7,642) State and local ​ (3,239) ​ (26,580) ​ (29,819) Income tax (benefit) expense ​ $ (6,769) ​ $ (134,199) ​ $ (140,967) 2019: ​ ​ ​ U.S. federal ​ $ (2,960) ​ $ 67,975 ​ $ 65,015 Foreign ​ 5,812 ​ 1,169 ​ 6,981 State and local ​ 10,704 ​ 9,242 ​ 19,946 Income tax expense ​ $ 13,556 ​ $ 78,386 ​ $ 91,942 2018: ​ ​ ​ U.S. federal ​ $ (58) ​ $ 65,976 ​ $ 65,918 Foreign ​ 11,752 ​ 626 ​ 12,378 State and local ​ 11,268 ​ 6,291 ​ 17,559 Income tax expense ​ $ 22,962 ​ $ 72,893 ​ $ 95,855 ​ Recorded income tax (benefit) expense differed from amounts computed by applying the U.S. federal income tax rate of 21% for the years ended December 31, 2020, 2019 and 2018 to (loss) income before income taxes as a result of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 ​ 2018 Computed "expected" federal income tax (benefit) expense ​ $ (109,842) ​ $ 65,470 ​ $ 86,490 Effect of noncontrolling interest income distribution ​ (8,671) ​ (8,558) ​ (8,401) Change in valuation allowance ​ (2,482) ​ 15,469 ​ 1,663 Effect of state and local income taxes, net of federal tax benefit ​ (14,356) ​ 18,622 ​ 12,980 Deductible compensation in excess of book ​ 773 ​ (2,029) ​ (5,392) Nondeductible compensation ​ 951 ​ 635 ​ 1,167 Effect of foreign income taxes ​ (4,072) ​ 2,084 ​ 4,544 Effect of foreign earnings earned and remitted in the same year ​ — ​ (302) ​ 2,317 Effect of foreign tax credits ​ (528) ​ (407) ​ (996) Other, net ​ (2,740) ​ 958 ​ 1,483 Income tax (benefit) expense ​ $ (140,967) ​ $ 91,942 ​ $ 95,855 ​ In connection with emergence from Chapter 11, the Company’s prepetition debt securities, primarily the prepetition notes issued by Six Flags, Inc. (which changed its corporate name to Six Flags Entertainment Corporation (Holdings) upon emergence from bankruptcy in 2010) and SFO, were extinguished. Absent an exception, a debtor recognizes cancellation of debt income ("CODI") upon discharge of its outstanding indebtedness for an amount of consideration that is less than its adjusted issue price. The Internal Revenue Code ("IRC") provides that a debtor in a bankruptcy case may exclude CODI from income but must reduce certain of its tax attributes by the amount of any CODI realized as a result of the consummation of a plan of reorganization. The amount of CODI realized by a taxpayer is the adjusted issue price of any indebtedness discharged less the sum of (i) the amount of cash paid, (ii) the issue price of any new indebtedness issued and (iii) the fair market value of any other consideration, including equity, issued. As a result of the market value of our equity upon emergence from Chapter 11 bankruptcy proceedings, we were able to retain a significant portion of our federal net operating losses (“NOLs”) and state NOLs (collectively, the "Tax Attributes") after reduction of the Tax Attributes for CODI realized on emergence from Chapter 11. As a result of emergence from Chapter 11, the Company’s NOLs were reduced by approximately $804.8 million of CODI. Sections 382 and 383 of the IRC impose an annual limitation on the utilization of NOLs and other favorable Tax Attribute carryforwards that a corporation has at the time of a so-called "ownership change" within the meaning of IRC Section 382. The Company’s issuance of stock pursuant to its reorganization under Chapter 11 in 2010 resulted in such an ownership change. The limitation amount is the product of the value of the Company, computed under special rules that apply to a bankruptcy reorganization, and a published rate that applied for the month the Company emerged from Chapter 11. The Company’s limitation amount is approximately $32.5 million for each year to which NOLs and other Tax Attribute carryforwards that existed at emergence are carried. As a result of the Section 382 limitation, the Company may have a cash tax liability in future years even though its deferred tax assets have not been exhausted. A subsequent ownership change could further limit the Company’s utilization of NOLs and other Tax Attributes if a smaller limitation resulted from the subsequent ownership change or applied to NOLs and other Tax Attributes accumulated after emergence from Chapter 11. Substantially all of our future taxable temporary differences (deferred tax liabilities) relate to the different financial accounting and tax depreciation methods and periods for property and equipment ( 20 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Deferred tax assets ​ $ 326,023 ​ $ 191,349 Less: Valuation allowance ​ 128,159 ​ 130,641 Net deferred tax assets ​ 197,864 ​ 60,708 Deferred tax liabilities ​ 299,695 ​ 307,829 Net deferred tax liability ​ $ 101,831 ​ $ 247,121 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Deferred tax assets: ​ ​ Federal net operating loss carryforwards ​ $ 115,168 ​ $ 12,615 State net operating loss carryforwards ​ 118,063 ​ 107,303 Deferred compensation ​ 9,307 ​ 8,240 Foreign tax credits ​ 21,367 ​ 20,469 Alternative minimum tax credits ​ — ​ 3,296 Accrued insurance, pension liability and other ​ 62,118 ​ 39,426 Total deferred tax assets ​ $ 326,023 ​ $ 191,349 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ Property and equipment ​ $ 220,927 ​ $ 226,872 Intangible assets and other ​ 78,768 ​ 80,957 Total deferred tax liabilities ​ $ 299,695 ​ $ 307,829 ​ As of December 31, 2020, we had approximately $0.6 billion and $6.3 billion of net operating loss carryforwards available for U.S. federal income tax and state income tax purposes, respectively, that expire through 2030 and 2038, respectively. Foreign tax credits of $21.4 million expire between 2021 and 2027. We have a valuation allowance of $128.2 million and $130.6 million as of December 31, 2020 and 2019, respectively, due to uncertainties related to our ability to utilize some of our deferred tax assets before they expire. We analyze our ability to use our foreign tax credits based on our most probable outcome for future foreign sourced income. Based on that analysis, we have determined it is not more likely than not that some of our foreign tax credits will not be fully utilized and have established a valuation allowance of approximately $18.0 million at December 31, 2020. The remainder of our valuation allowance at December 31, 2020 and 2019 was based on our inability to use state deferred tax assets related to NOLs that were generated in states where we no longer do business or where we have consistently not generated taxable income. The change in valuation allowance is all attributable to income from operations. Our unrecognized tax benefit as of each of December 31, 2020 and 2019 was $25.4 million and $25.7 million, respectively. We classify interest and penalties attributable to income taxes as part of income tax expense. Due to the Company’s NOL position, we have not accrued any penalties and interest.

Preferred Stock, Common Stock a

Preferred Stock, Common Stock and Other Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Preferred Stock, Common Stock and Other Stockholders' Equity
Preferred Stock, Common Stock and Other Stockholders' Equity	12. Preferred Stock, Common Stock and Other Stockholders’ Equity Common Stock As of December 31, 2020, the number of authorized shares of common stock was 280,000,000, of which 85,075,901 shares were outstanding, 4,375,000 shares were reserved for future issuance through our Long-Term Incentive Plan, and 1,579,000 shares were reserved for future issuance through the ESPP. Pursuant to the ESPP, Holdings’ common stock may be issued from authorized and unissued shares, treasury shares or shares purchased on the open market. On March 30, 2017, Holdings announced that its Board of Directors approved a new stock repurchase plan that permits Holdings to repurchase an incremental $500 million in shares of Holdings’ common stock (the "March 2017 Stock Repurchase Plan"). As of February 19, 2021, Holdings had repurchased 4,607,000 shares at a cumulative cost of approximately $268.3 million and an average price per share of $58.25 under the March 2017 Stock Repurchase Plan, leaving approximately $231.7 million available for permitted repurchases. During the years ended December 31, 2020, 2019 and 2018, Holdings’ Board of Directors declared and paid quarterly cash dividends per share of common stock as follows: ​ ​ ​ ​ ​ ​ ​ Dividends ​ ​ Paid ​ Per Share 2020: ​ ​ First Quarter ​ $ 0.25 2019: ​ Fourth Quarter ​ $ 0.83 Third Quarter ​ $ 0.82 Second Quarter ​ $ 0.82 First Quarter ​ $ 0.82 2018: ​ Fourth Quarter ​ $ 0.82 Third Quarter ​ $ 0.78 Second Quarter ​ $ 0.78 First Quarter ​ $ 0.78 ​ Preferred Stock As of December 31, 2020, the number of authorized shares of preferred stock was 5,000,000, none issued Shareholder Rights Plan On March 31, 2020, Holdings announced that its Board of Directors declared a dividend of one preferred share purchase right (a “Right”) payable on April 10, 2020, for each share of common stock to the shareholders of record on that date. In connection with the Rights, Holdings and Computershare Trust Company, N.A., as rights agent, entered into a Rights Agreement, dated as of March 31, 2020 (the “Rights Agreement”). Each Right entitles the registered holder to purchase from Holdings one one-thousandth one one-thousandth Agreement. The Rights Plan has a one-year term, expiring on March 30, 2021. The Rights Plan may also be terminated, or the rights may be redeemed, prior to the scheduled expiration of the Rights Plan under certain other circumstances. Accumulated Other Comprehensive Loss The balances for each component of accumulated other comprehensive loss are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ ​ Translation ​ Cash Flow ​ Defined Benefit ​ Income ​ Comprehensive (Amounts in thousands) Adjustment Hedges Plans Taxes Loss Balance as of December 31, 2017 ​ $ (28,822) ​ $ — ​ $ (41,959) ​ $ 6,900 ​ $ (63,881) Net current period change ​ 1,470 ​ — ​ 167 ​ (351) ​ 1,286 Amounts reclassified from AOCL ​ — ​ — ​ 721 ​ (185) ​ 536 Effects of Adoption of ASU 2018-02 ​ ​ — ​ ​ — ​ ​ — ​ ​ (9,439) ​ ​ (9,439) Balance as of December 31, 2018 ​ $ (27,352) ​ $ — ​ $ (41,071) ​ $ (3,075) ​ $ (71,498) Net current period change ​ 5,168 ​ (484) ​ (9,006) ​ 1,283 ​ (3,039) Amounts reclassified from AOCL ​ ​ — ​ ​ (1,046) ​ ​ 795 ​ ​ 78 ​ ​ (173) Balances at December 31, 2019 ​ $ (22,184) ​ $ (1,530) ​ $ (49,282) ​ $ (1,714) ​ $ (74,710) Net current period change ​ (5,228) ​ (33,902) ​ (9,345) ​ 11,968 ​ (36,507) Amounts reclassified from AOCL ​ — ​ 3,685 ​ 985 ​ (1,165) ​ 3,505 Amounts reclassified due to de-designation ​ ​ — ​ ​ 14,928 ​ ​ — ​ ​ (3,720) ​ ​ 11,208 Balances at December 31, 2020 ​ $ (27,412) ​ $ (16,819) ​ $ (57,642) ​ $ 5,369 ​ $ (96,504) ​ The Company had the following reclassifications out of accumulated other comprehensive loss during the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of Reclassification from AOCL ​ ​ ​ Year Ended December 31, Component of AOCL Location of Reclassification into Income 2020 ​ 2019 ​ 2018 Amortization of loss on interest rate hedge Interest expense $ 3,685 ​ $ (1,046) ​ $ — ​ Income tax benefit (917) ​ 276 ​ — ​ Net of tax $ 2,768 ​ $ (770) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of deferred actuarial loss and prior service cost Operating expenses $ 985 ​ $ 795 ​ $ 721 ​ Income tax expense (248) ​ (198) ​ (185) ​ Net of tax $ 737 ​ $ 597 ​ $ 536 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications $ 3,505 ​ $ (173) ​ $ 536 ​

Pension Benefits

Pension Benefits	12 Months Ended
	Dec. 31, 2020
Pension Benefits
Pension Benefits	13. Pension Benefits As part of the acquisition of Former SFEC, we assumed the obligations related to the SFTP Defined Benefit Plan (the "SFTP Benefit Plan"). The SFTP Benefit Plan covered substantially all of SFTP’s employees. During 1999, the SFTP Benefit Plan was amended to cover substantially all of our domestic full-time employees. During 2004, the SFTP Benefit Plan was further amended to cover certain seasonal workers, retroactive to January 1, 2003. The SFTP Benefit Plan permits normal retirement at age 65, with early retirement at ages 55 through 64 upon attainment of 10 years of credited service. The early retirement benefit is reduced for benefits commencing before age 62. Plan benefits are calculated according to a benefit formula based on age, average compensation over the highest consecutive five-year period during the employee’s last ten years of employment and years of service. The SFTP Benefit Plan assets are invested primarily in equity and fixed income securities, as well as alternative investments, such as hedge funds. The SFTP Benefit Plan does not have significant liabilities other than benefit obligations. Under our funding policy, contributions to the SFTP Benefit Plan are determined using the projected unit credit cost method. This funding policy meets the requirements under the Employee Retirement Income Security Act of 1974 (“ERISA”). We froze our pension plan effective March 31, 2006, pursuant to which most participants no longer earned future pension benefits. Effective February 16, 2009, the remaining participants in the pension plan no longer earned future benefits. Obligations and Funded Status The following table sets forth the change in our benefit plan obligation and fair value of plan assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Change in benefit obligation: ​ ​ ​ Beginning balance ​ $ 221,458 ​ $ 201,752 ​ $ 218,746 Interest cost ​ 6,431 ​ 7,993 ​ 7,386 Actuarial loss (gain) ​ 18,243 ​ 25,632 ​ (16,324) Benefits paid ​ (9,006) ​ (13,919) ​ (8,056) Benefit obligation at end of period ​ $ 237,126 ​ $ 221,458 ​ $ 201,752 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in fair value of plan assets: ​ ​ ​ Beginning balance ​ $ 205,463 ​ $ 184,758 ​ $ 190,534 Actual return on assets ​ 21,987 ​ 29,815 ​ (2,497) Employer contributions ​ 1,500 ​ 6,000 ​ 6,000 Administrative fees ​ (9,006) ​ (13,918) ​ (1,223) Benefits paid ​ (1,171) ​ (1,192) ​ (8,056) Fair value of plan assets at end of period ​ $ 218,773 ​ $ 205,463 ​ $ 184,758 ​ Employer contributions and benefits paid in the above table include only those amounts contributed directly to, or paid directly from, plan assets. As of December 31, 2020 and 2019, the SFTP Benefit Plan’s projected benefit obligation exceeded the fair value of SFTP Benefit Plan assets resulting in the SFTP Benefit Plan being underfunded by $18.4 million and $16.0 million, respectively. The underfunded amount is recognized in other long-term liabilities in our consolidated balance sheets. Other net periodic pension benefit is disclosed within the consolidated statement of operations due to the adoption of ASU 2017-07. We use December 31 as our measurement date. The weighted average assumptions used to determine benefit obligations are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Discount rate 2.20 % 3.00 % Rate of compensation increase N/A N/A ​ ​ Net periodic benefit cost and other comprehensive income (loss) The following table sets forth the components of net periodic benefit cost and other comprehensive income (loss): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Net periodic benefit cost: ​ ​ ​ Service cost $ 1,200 ​ $ 1,300 ​ $ 1,300 Interest cost 6,431 ​ 7,993 ​ 7,386 Expected return on plan assets (13,119) ​ (13,296) ​ (13,737) Amortization of net actuarial loss 985 ​ 795 ​ 721 Total net periodic benefit $ (4,503) ​ $ (3,208) ​ $ (4,330) ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income: ​ ​ Current year actuarial (gain) loss $ (9,345) ​ $ (9,006) ​ $ 167 Recognized net actuarial loss 985 ​ 795 ​ 721 Total other comprehensive (gain) loss $ (8,360) ​ $ (8,211) ​ $ 888 ​ As of December 31, 2020 and 2019, we have recorded $64.6 million (net of tax expense of $7.0 million) and $56.1 million (net of tax expense of $6.8 million), respectively, in accumulated other comprehensive loss in our consolidated balance sheets. We anticipate that $1.4 million will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2021. The weighted average assumptions used to determine net costs are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Discount rate ​ 3.00 % 4.05 % 3.45 % Rate of compensation increase ​ N/A N/A N/A ​ Expected return on plan assets ​ 6.50 % 7.25 % 7.25 % Corridor ​ 10.00 % 10.00 % 10.00 % Average future life expectancy (in years) ​ 25.70 26.87 27.77 ​ ​ The discount rate assumption was developed based on high-quality corporate bond yields as of the measurement date. High quality corporate bond yield indices on over 500 AA high grade bonds are considered when selecting the discount rate. The return on plan assets assumption was developed based on consideration of historical market returns, current market conditions, and the SFTP Benefit Plan’s past experience. Estimates of future market returns by asset category are reflective of actual long-term historical returns. Overall, it was projected that the SFTP Benefit Plan could achieve a 6.50% net return over time based on a consistent application of the existing asset allocation strategy and a continuation of the SFTP Benefit Plan’s policy of monitoring manager performance. Description of Investment Committee and Strategy The Investment Committee is responsible for managing the investment of SFTP Benefit Plan assets and ensuring that the SFTP Benefit Plan’s investment program is in compliance with all provisions of ERISA, other relevant legislation, related SFTP Benefit Plan documents and the Statement of Investment Policy. The Investment Committee has retained several mutual funds, commingled funds and/or investment managers to manage SFTP Benefit Plan assets and implement the investment process. The investment managers, in implementing their investment processes, have the authority and responsibility to select appropriate investments in the asset classes specified by the terms of the applicable prospectus or other investment manager agreements with the SFTP Benefit Plan. The primary financial objective of the SFTP Benefit Plan is to secure participant retirement benefits. To achieve this, the key objective in the SFTP Benefit Plan’s financial management is to promote stability and, to the extent appropriate, growth in funded status. Other related and supporting financial objectives are also considered in conjunction with a comprehensive review of current and projected SFTP Benefit Plan financial requirements. The assets of the fund are invested to achieve the greatest reward for the SFTP Benefit Plan consistent with a prudent level of risk. The asset return objective is to achieve, as a minimum over time, the passively managed return earned by market index funds, weighted in the proportions outlined by the asset class exposures in the SFTP Benefit Plan’s long-term target asset allocation. The SFTP Benefit Plan’s portfolio may be allocated across several hedge fund styles and strategies. Plan Assets The target allocations for plan assets are 4% domestic equity securities, 63% fixed income securities, 19% international equity securities, and 14% alternative investments. Equity securities primarily include investments in large-cap companies located in the United States and abroad. Fixed income securities include bonds and debentures issued by domestic and foreign private and governmental issuers. Alternative investments are comprised of hedge fund of funds. The following table presents the categories of our plan assets and the related levels of inputs in the fair value hierarchy used to determine the fair value, as defined in Note 2(c): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements as of December 31, 2020 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs (Amounts in thousands) ​ Total ​ (Level 1) ​ (Level 2) ​ (Level 3) ASSET CATEGORY: ​ ​ ​ ​ Equity Securities: ​ ​ ​ ​ Large-Cap Disciplined Equity (a) ​ $ 8,065 ​ $ 8,065 ​ $ — ​ $ — International Equity (b) ​ 42,178 ​ 42,178 ​ — ​ — Fixed Income: ​ ​ ​ ​ ​ Long Duration Fixed Income (c) ​ 138,399 ​ 138,399 ​ — ​ — Alternatives: ​ ​ ​ ​ Other Investments (f) ​ 30,131 ​ — ​ — ​ — Fair Value of Plan Assets ​ $ 218,773 ​ $ 188,642 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements as of December 31, 2019 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs (Amounts in thousands) ​ Total ​ (Level 1) ​ (Level 2) ​ (Level 3) ASSET CATEGORY: ​ ​ ​ ​ Equity Securities: ​ ​ ​ ​ Large-Cap Disciplined Equity (a) ​ $ 6,844 ​ $ 6,844 ​ $ — ​ $ — International Equity (b) ​ 35,962 ​ 35,962 ​ — ​ — Fixed Income: ​ ​ ​ ​ Long Duration Fixed Income (c) ​ 133,592 ​ 133,592 ​ — ​ — High Yield (d) ​ — ​ — ​ — ​ — Emerging Markets Debt (e) ​ — ​ — ​ — ​ — Alternatives: ​ ​ ​ ​ Other Investments (f) ​ 29,065 ​ — ​ — ​ — Fair Value of Plan Assets ​ $ 205,463 ​ $ 176,398 ​ $ — ​ $ — (a) These categories are comprised of mutual funds actively traded on the registered exchanges or over the counter markets. The mutual funds are invested in equity securities of U.S. issuers. (b) This category consists of mutual funds invested primarily in equity securities (common stocks, securities that are convertible into common stocks, preferred stocks, warrants and rights to subscribe to common stocks) of non-U.S. issuers purchased in foreign markets. The mutual funds are actively traded on U.S. or foreign registered exchanges, or the over-the-counter markets. (c) The assets are comprised of U.S. Treasury Separate Trading of Registered Interest and Principal of Securities ("U.S. Treasury STRIPS") and mutual funds which are actively traded on the registered exchanges. The mutual funds are invested primarily in high quality government and corporate fixed income securities, as well as synthetic instruments or derivatives having economic characteristics similar to fixed income securities. (d) The high yield portion of the fixed income portfolio consists of mutual funds invested primarily in fixed income securities that are rated below investment grade. The mutual funds are actively traded on the registered exchanges. (e) The emerging debt portion of the portfolio consists of mutual funds primarily invested in the debt securities of government, government-related and corporate issuers in emerging market countries and of entities organized to restructure outstanding debt of such issuers. The mutual funds are actively traded on the registered exchanges. (f) Common/collective trust investments that are measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the total fair value of plan assets. The Company has participant redemptions restricted to the last business day of the quarter, with either a 65 or 90 day period redemption notice. Expected Cash Flows The following table summarizes expected employer contributions and future benefit payments: ​ ​ ​ ​ ​ (Amounts in thousands) ​ ​ Expected contributions to plan trusts ​ 2021 ​ $ — Total expected contributions ​ $ — ​ ​ ​ ​ Expected benefit payments: ​ 2021 ​ $ 10,578 2022 ​ 11,072 2023 ​ 11,407 2024 ​ 11,709 2025 ​ 11,958 2026 through 2030 ​ 60,744 Total expected benefit payments ​ $ 117,468 ​

(Loss) Earnings Per Common Shar

(Loss) Earnings Per Common Share	12 Months Ended
	Dec. 31, 2020
(Loss) Earnings Per Common Share
(Loss) Earnings Per Common Share	14. (Loss) Earnings Per Common Share Basic (loss) earnings per common share is computed by dividing net (loss) income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed by dividing net income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding during the period and the effect of all dilutive common stock equivalents. In periods where there is a net loss, diluted loss per common share is equal to basic loss per common share, since the effect of including any common stock equivalents would be antidilutive. For the years ended December 31, 2019 and 2018, the computation of diluted earnings per common share included the effect of 0.6 million and 1.3 million dilutive stock options and restricted stock units, respectively. For the years ended December 31, 2020, 2019 and 2018, the computation of diluted (loss) earnings per common share excluded the effect of 6.3 million, 3.5 million and 0.7 million antidilutive stock options and restricted stock units, respectively. (Loss) earnings per common share for the years ended December 31, 2020, 2019 and 2018 was calculated as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, (Amounts in thousands, except per share amounts) 2020 2019 2018 Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ $ (423,380) ​ $ 179,065 ​ $ 275,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding—basic ​ 84,800 ​ 84,348 ​ 84,100 Effect of dilutive stock options and restricted stock units ​ — ​ 620 ​ 1,345 Weighted-average common shares outstanding—diluted ​ 84,800 ​ 84,968 ​ 85,445 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Loss) earnings per share—basic ​ $ (4.99) ​ $ 2.12 ​ $ 3.28 (Loss) earnings per share—diluted ​ $ (4.99) ​ $ 2.11 ​ $ 3.23 ​

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies
Commitments and Contingencies	15. Commitments and Contingencies Partnership Parks On April 1, 1998, we acquired all of the capital stock of Former SFEC for $976.0 million, paid in cash. In addition to our obligations under outstanding indebtedness and other securities issued or assumed in the Former SFEC acquisition, we also guaranteed certain contractual obligations relating to the Partnership Parks. Specifically, we guaranteed the obligations of the general partners of those partnerships to (i) make minimum annual distributions (including rent) of approximately $75.2 million in 2021 (subject to cost of living adjustments) to the limited partners in the Partnership Parks (based on our ownership of units as of December 31, 2020, our share of the distribution will be approximately $33.3 million) and (ii) make minimum capital expenditures at each of the Partnership Parks during rolling five-year periods, based generally on 6% of the Partnership Parks’ revenues. Cash flow from operations at the Partnership Parks is used to satisfy these requirements, before any funds are required from us. We also guaranteed the obligation of our subsidiaries to annually purchase all outstanding limited partnership units to the extent tendered by the unit holders (the "Partnership Park Put"). The agreed price for units tendered in the Partnership Park Put is based on a valuation of each of the respective Partnership Parks (the "Specified Price") that is the greater of (a) a valuation for each of the respective Partnership Parks derived by multiplying such park’s weighted average four year EBITDA (as defined in the agreements that govern the partnerships) by a specified multiple (8.0 in the case of SFOG and 8.5 in the case of SFOT) and (b) a valuation derived from the highest prices previously paid for the units of the Partnership Parks by certain entities. In light of the temporary suspension of operations of the Partnership Parks due to the COVID-19 pandemic in March 2020, which would cause the value of the limited partnership units of the Partnership Parks to decrease in 2021 and thereafter, we adjusted our annual offer to purchase these units to set a minimum price floor for all future purchases. Pursuant to the valuation methodologies described in the preceding sentence, the Specified Price for the Partnership Parks, if determined as of December 31, 2020 is $409.7 million in the case of SFOG and $527.4 million in the case of SFOT. As of December 31, 2020, we owned approximately 31.4% and 53.9% of the Georgia limited partner interests and Texas limited partner interests, respectively. Our obligations with respect to SFOG and SFOT will continue until 2027 and 2028, respectively. In 2027 and 2028, we will have the option to purchase all remaining units in the Georgia limited partner and the Texas limited partner, respectively, at a price based on the Specified Price, increased by a cost of living adjustment. Pursuant to the 2020 annual offer, we purchased 0.375 units from the Georgia partnership for approximately $1.5 million and 1.5675 units from the Texas partnership for approximately $3.4 million in May 2020. Pursuant to the 2019 annual offer, we did not purchase any units from the Georgia partnership and we purchased 0.1 units from the Texas partnership for approximately $0.2 million in May 2019. As we purchase additional units, we are entitled to a proportionate increase in our share of the minimum annual distributions. The maximum unit purchase obligations for 2021 at both parks aggregates to approximately $523.4 million, representing approximately 68.6% of the outstanding units of SFOG and 46.1% of the outstanding units of SFOT. The $350.0 million accordion feature on the Second Amended and Restated Term Loan B under the Second Amended and Restated Credit Facility is available for borrowing for future "put" obligations if necessary. In connection with our acquisition of the Former SFEC, we entered into the Subordinated Indemnity Agreement with certain of the Company’s entities, Time Warner and an affiliate of Time Warner (an indirect subsidiary of AT&T Inc. as a result of a merger in 2018), pursuant to which, among other things, we transferred to Time Warner (which has guaranteed all of our obligations under the Partnership Park arrangements) record title to the corporations which own the entities that have purchased and will purchase limited partnership units of the Partnership Parks, and we received an assignment from Time Warner of all cash flow received on such limited partnership units, and we otherwise control such entities. In addition, we issued preferred stock of the managing partner of the partnerships to Time Warner. In the event of a default by us under the Subordinated Indemnity Agreement or of our obligations to our partners in the Partnership Parks, these arrangements would permit Time Warner to take full control of both the entities that own limited partnership units and the managing partner. If we satisfy all such obligations, Time Warner is required to transfer to us the entire equity interests of these entities. The 2018 merger of Time Warner and AT&T Inc. did not affect the Time Warner guarantee of our obligations under the Subordinated Indemnity Agreement. We incurred $9.1 million of capital expenditures at these parks during the 2020 season and intend to incur approximately $10.2 million of capital expenditures at these parks for the 2021 season, an amount in excess of the minimum required expenditure. Cash flows from operations at the Partnership Parks will be used to satisfy the annual distribution and capital expenditure requirements, before any funds are required from us. The Partnership Parks used approximately $8.4 million of cash in 2020 from operating activities after deduction of capital expenditures and excluding the impact of short-term intercompany advances from or payments to Holdings. As of December 31, 2020 and 2019, we had total loans receivable outstanding of $288.3 million and $239.3 million, respectively, from the partnerships that own the Partnership Parks, primarily to fund the acquisition of Six Flags White Water Atlanta, and to make capital improvements and distributions to the limited partners. License Agreements We are party to a license agreement pursuant to which we have the exclusive right on a long-term basis to theme park use in the United States and Canada (excluding the Las Vegas, Nevada metropolitan area) of all animated, cartoon and comic book characters that Warner Bros. and DC Comics have the right to license for such use. The term of the agreement expires in 2053. The license fee is payable on a per-theme park basis, and is subject to CPI increases and scheduled adjustments, including periodic market resets. In November 1999, we entered into license agreements pursuant to which we have the exclusive right on a long-term basis to parks use in Europe, Central and South America of all animated, cartoon and comic book characters that Warner Bros. and DC Comics have the right to license for such use. Under such agreements, the license fee is based on specified percentages of the gross revenues of the applicable parks. Insurance We maintain insurance of the types and in amounts that we believe are commercially reasonable and that are available to businesses in our industry. We maintain multi-layered general liability policies that provide for excess liability coverage of up to $100.0 million per occurrence. For incidents arising on or after December 31, 2008, our self-insured retention is $2.0 million, followed by a $0.5 million deductible per occurrence applicable to all claims in the policy year for our domestic parks and our park in Canada and a nominal amount per occurrence for our parks in Mexico. Defense costs are in addition to these retentions. Our general liability policies cover the cost of punitive damages only in certain jurisdictions. Based upon reported claims and an estimate for incurred, but not reported claims, we accrue a liability for our retention contingencies. For workers’ compensation claims arising after November 15, 2003, our deductible is $0.75 million. We also maintain fire and extended coverage, business interruption, terrorism and other forms of insurance typical to businesses in this industry. The all peril property coverage policies insure our real and personal properties (other than land) against physical damage resulting from a variety of hazards. Additionally, we maintain information security and privacy liability insurance in the amount of $10.0 million with a $0.25 million retention per event. We generally renegotiate our insurance policies on an annual basis. The majority of our current insurance policies expire on December 31, 2021. We cannot predict the level of the premiums that we may be required to pay for subsequent insurance coverage, the level of any retention applicable thereto, the level of aggregate coverage available or the availability of coverage for specific risks. Capital Expenditures We plan to strategically reinvest in our properties to improve the guest experience. ​ Litigation Privacy Class Action Lawsuits ​ On January 7, 2016, a putative class action complaint was filed against Holdings in the Circuit Court of Lake County, Illinois. On April 22, 2016, Great America, LLC was added as a defendant. The complaint asserts that we violated the Illinois Biometric Information Privacy Act ("BIPA") in connection with the admission of season pass holders and members through the finger scan program that commenced in the 2014 operating season at Six Flags Great America in Gurnee, Illinois, and seeks statutory damages, attorneys’ fees and an injunction. An aggrieved party under BIPA may recover (i) $1,000 if a company is found to have negligently violated BIPA or (ii) $5,000 if found to have intentionally or recklessly violated BIPA, plus reasonable attorneys’ fees in each case. The complaint does not allege that any information was misused or disseminated. On April 7, 2017, the trial court certified two questions for consideration by the Illinois Appellate Court of the Second District. On June 7, 2017, the Illinois Appellate Court granted our motion to appeal. Accordingly, two questions regarding the interpretation of BIPA were certified for consideration by the Illinois Appellate Court. On December 21, 2017, the Illinois Appellate Court found in our favor, holding that the plaintiff had to allege more than a technical violation of BIPA and had to be injured in some way in order to have a right of action. On March 1, 2018, the plaintiff filed a petition for leave to appeal to the Illinois Supreme Court. On May 30, 2018, the Illinois Supreme Court granted the plaintiff’s leave to appeal and oral arguments were heard on November 20, 2018. On January 25, 2019, the Illinois Supreme Court found in favor of the plaintiff, holding that the plaintiff does not need to allege an actual injury beyond the violation of his rights under BIPA in order to proceed with a complaint. We intend to continue to vigorously defend ourselves against this litigation. The amount we have recorded is based on our estimate of the probable outcome of this litigation. ​ During 2017, four putative class action complaints were filed against Holdings or one of its subsidiaries. Complaints were filed on August 11, 2017, in the Circuit Court of Lake County, Illinois; on September 1, 2017, in the United States District Court for the Northern District of Georgia; on September 11, 2017, in the Superior Court of Los Angeles County, California; and on November 30, 2017, in the Superior Court of Ocean County, New Jersey. The complaints allege that we, in violation of federal law, printed more than the last five digits of a credit or debit card number on customers’ receipts and/or the expiration dates of those cards. A willful violation may subject a company to liability for actual damages or statutory damages between $100 and $1,000 per person, punitive damages in an amount determined by a court and reasonable attorneys’ fees, all of which are sought by the plaintiffs. The complaints do not allege that any information was misused. On October 20, 2020, the parties entered into a settlement agreement to resolve the lawsuits, for an immaterial amount, and preliminary approval was granted by the court on December 3, 2020 Securities Class Action Lawsuits ​ In February 2020, two putative securities class action complaints were filed against Holdings and certain of its former executive officers (collectively, the “defendants”) in the U.S. District Court for the Northern District of Texas. On March 2, 2020, the two cases were consolidated in an action captioned Electrical Workers Pension Fund Local 103 I.B.E.W. v. Six Flags Entertainment Corp., et al. ​ Stockholder Derivative Lawsuits ​ On March 20, 2020, a putative stockholder derivative lawsuit was filed on behalf of nominal defendant Holdings, by Mr. Mark Schwartz in the U.S. District Court for the Northern District of Texas against certain of its current and former executive officers and directors (the “individual defendants”) in an action captioned Schwartz v. Reid-Anderson, et al. , Case No. 4:20-cv-00262-P (N.D. Tex.). In April 2020, two additional stockholder derivative lawsuits, making substantially identical allegations as the Schwartz complaint, were filed on behalf of nominal defendant Holdings by Trustees of the St. Clair County Employees’ Retirement System and Mr. Mehmet Ali Albayrak in the U.S. District Court for the Northern District of Texas in actions captioned Martin, et al. v. Reid-Anderson, et al. , Case No. 4:20-cv-00311-P (N.D. Tex.) and Albayrak v. Reid-Anderson, et al. , Case No. 4:20-cv-00312-P (N.D. Tex.), respectively. On April 8, 2020, plaintiffs in all three of these putative derivative actions moved to consolidate the three actions and to appoint lead counsel. On May 8, 2020, the court granted the plaintiffs’ motion to consolidate. The consolidated action is captioned In re Six Flags Entertainment Corporation Derivative Litigation , Case No. 4:20-cv-00262-P (N.D. Tex.). On August 10, 2020, plaintiffs filed a consolidated derivative complaint. The consolidated derivative complaint alleges breach of fiduciary duty, insider selling, waste of corporate assets, unjust enrichment, and contribution for violations of federal securities laws. The consolidated derivative complaint references, and makes many of the same allegations, as are set forth in the Electrical Workers litigation, alleging, among other things, that the individual defendants breached their fiduciary duties, committed waste, are liable for contribution for, or were unjustly enriched by making, failing to correct, or failing to implement adequate internal controls relating to alleged materially false or misleading statements or omissions regarding the Company’s business, operations and growth prospects, specifically with respect to the prospects of the development of its Six Flags branded parks in China and the financial health of its partner, Riverside Investment Group Co. Ltd. The consolidated derivative complaint also alleges that a former officer and director sold shares of the Company while allegedly in possession of material non-public information concerning the same. On September 9, 2020, Holdings and the individual defendants filed a motion to dismiss the consolidated complaint, which motion was fully briefed as of October 23, 2020 and remains pending. We believe that these complaints are without merit and intend to defend these lawsuits vigorously. However, there can be no assurance regarding the ultimate outcome of these lawsuits. ​ On May 5, 2020, a putative stockholder derivative lawsuit was filed on behalf of nominal defendant Holdings, by Mr. Richard Francisco in the District Court for Dallas County, Texas, 160th Judicial District, against certain of its current and former executive officers and directors (the “individual defendants”) in an action captioned Francisco v. Reid-Anderson, et al. , Case No. DC-20-06425 (160th Dist. Ct., Dallas Cty., Tex.) (the “Francisco action”). The petition in the Francisco action alleges breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets. The petition in the Francisco action references, and makes many of the same allegations, as are set forth in the Electrical Workers litigation, alleging, among other things, that the individual defendants breached their fiduciary duties, were unjustly enriched by, abused their control, committed gross mismanagement, and committed waste by making, failing to correct, or failing to implement adequate internal controls relating to alleged materially false or misleading statements or omissions regarding the Company’s business, operations and growth prospects, specifically with respect to the prospects of the development of its Six Flags branded parks in China and the financial health of its partner, Riverside Investment Group Co, Ltd. The petition also alleges that a former officer and director engaged in insider trading. On May 28, 2020, the parties in the Francisco action filed a joint motion to stay proceedings through the resolution of the forthcoming motion to dismiss the Electrical Workers litigation. On June 3, 2020, the court granted the joint motion to stay proceedings. On June 12, 2020, an additional stockholder derivative lawsuit, making substantially identical allegations as the Francisco petition, was filed on behalf of nominal defendant Holdings in the District Court for Dallas County, Texas, 298th Judicial District on behalf of putative stockholder Mr. Cliff Bragdon in an action captioned Bragdon v. Reid-Anderson, et al. (298th Dist. Ct., Dallas Cty., Tex.) (the “Bragdon action”). On July 10, 2020, the court granted an agreed motion filed by the parties in the Francisco and Bragdon actions to consolidate cases, to accept service and an unopposed motion to appoint co-lead and liaison counsel, and to stay both the Francisco and Bragdon actions through resolution of the motion to dismiss the Electrical Workers litigation. The consolidated state derivative action is captioned In re Six Flags Entertainment Corp. Derivative Litigation , Case No. DC-20-06425 (160th Dist. Ct., Dallas Cty., Tex.). On September 8, 2020, the parties to the consolidated state derivative action filed an agreed motion to transfer the case from Dallas County to Tarrant County, which motion was so ordered on September 27, 2020. The consolidated action is now captioned In re Six Flags Ent. Corp. Deriv. Litig., No. 096- 320958-20 (Tex. Dist. Ct., Tarrant Cty.). We believe that these complaints are without merit and intend to defend these lawsuits vigorously. However, there can be no assurance regarding the ultimate outcome of these Wage and Hour Class Action Lawsuits ​ On March 8, 2016, certain plaintiffs filed a complaint against one of our subsidiaries in the Superior Court of Massachusetts, Suffolk County, on behalf of a purported class of current and former employees of Six Flags New England. The complaint alleges violations of Massachusetts law governing employee overtime and rest breaks, and seeks damages in the form of unpaid wages for overtime and meal breaks and related penalties. On November 12, 2020, the parties entered into a settlement agreement to resolve the lawsuit, for an immaterial amount, and preliminary approval was granted by the court on December 3, 2020. On April 20, 2018, a complaint was filed against Holdings and Six Flags Concord, LLC in the Superior Court of Solano County, California, on behalf of a purported class of current and former employees of Six Flags Discovery Kingdom. On June 15, 2018, an amended complaint was filed adding Park Management Corp. as a defendant. The amended complaint alleges violations of California law governing, among other things, employee overtime, meal and rest breaks, wage statements, and seeks damages in the form of unpaid wages, and related penalties, and attorneys’ fees and costs. Following mediation on November 30, 2020, the parties agreed to a settlement in principle to resolve the lawsuit, for an immaterial amount. The settlement is subject to preliminary and final approval by the court On September 18, 2019, a complaint was filed against Magic Mountain LLC in the Superior Court of Los Angeles County, California, on behalf of a purported class of current and former employees of Six Flags Discovery Kingdom. An amended complaint was filed on November 24, 2019. On May 27, 2020, a copycat complaint was filed by the same law firm on behalf of a different named plaintiff alleging identical causes of action. The complaints allege violations of California law governing payment of wages, wage statements, and background checks, and seeks statutory damages under California law as well as under the Private Attorneys General Act, and attorneys’ fees costs. We intend to vigorously defend ourselves against this litigation. Since this litigation is in an early stage, the outcome is currently not determinable and a reasonable estimate of loss or range of loss cannot be made. ​ On February 14, 2020, a complaint was filed against Magic Mountain, LLC in the Superior Court of Los Angeles County, California, on behalf of a purported class of current and former employees of Six Flags Magic Mountain. The complaint alleges one cause of action for failure to furnish accurate, itemized wage statements in violation of California labor law, and seeks all applicable statutory penalties and attorneys’ fees and costs. Following mediation on January 13, 2021, the parties agreed to a settlement in principle to resolve the lawsuit, for an immaterial amount. The settlement is subject to preliminary and final approval by the court. ​ On February 20, 2020, a complaint was filed against Park Management Corp. in the Superior Court of Solano County, California, on behalf of a purported class of current and former employees of Six Flags Discovery Kingdom. The complaint alleges violations of California law governing payment of wages, wage statements, and background checks, and seeks statutory damages under California law and attorneys’ fees costs. We intend to vigorously defend ourselves against this litigation. Since this litigation is in an early stage, the outcome is currently not determinable and a reasonable estimate of loss or range of loss cannot be made. ​ COVID-19 Park Closure Lawsuits Since COVID-19 began affecting the operations of our parks in mid-March 2020, three similar purported class action complaints were filed against Holdings or one of its subsidiaries in the United States District Court for the Central District of California on April 10, 2020, April 13, 2020, and April 21, 2020. These complaints allege that we, in violation of California law, charged members and season passholders while the parks were closed and did not provide refunds for the amounts charged. The complaints seek compensatory damages, punitive damages, restitution, and unspecified injunctive relief. On September 9, 2020, the parties agreed to a settlement in principle to resolve the lawsuits, for an immaterial amount, which is subject to preliminary and final approval by the court Tax and other contingencies As of December 31, 2020 and 2019, we had a nominal amount of accrued liabilities for tax and other indemnification contingencies related to certain parks sold in previous years that could be recognized as recovery losses from discontinued operations in the future if such liabilities are not requested to be paid.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases
Leases	16. Leases On January 1, 2019, we adopted Topic 842 using the modified retrospective approach on leases with terms extending past January 1, 2019. Results for reporting periods beginning after January 1, 2019, are presented under Topic 842, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under Topic 840. As a result, we were not required to adjust our comparative period financial information for the effects of Topic 842 or make new lease disclosures for comparative prior periods before the date of adoption. See Note 2 ( u. Leases Upon adoption of Topic 842 on January 1, 2019, we recorded right-of-use assets and corresponding liabilities We have operating leases for amusement parks, land, vehicles, machinery and certain equipment. Our leases have remaining lease terms of less than one year to 45 years, some of which include an option to extend the underlying leases for up to 20 years, and some of which include an option to terminate the underlying lease within one year. For our noncancelable operating leases with such options to extend, because we may determine it is not reasonably certain we will exercise the option, the options are not considered in determining the lease term, and associated potential option payments are excluded from lease payments. Our leases generally do not include restrictive financial or other covenants. Payments due under the lease contracts include fixed payments and, for certain of our leases, variable payments. The components of lease cost for the year ended December 31, 2020 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands) ​ December 31, 2020 December 31, 2019 Finance Lease Expense ​ ​ ​ ​ ​ ​ Amortization of ROU assets ​ $ 248 ​ $ — Interest on lease liabilities ​ ​ 31 ​ ​ — Operating lease cost ​ ​ 24,166 ​ 24,890 Short-term lease cost ​ ​ 5,804 ​ ​ 6,925 Variable lease cost ​ ​ 4,816 ​ ​ 5,979 Total lease cost ​ $ 35,065 ​ $ 37,794 ​ Lease costs for the year ended December 31, 2020 and 2019 included minimum rental payments under operating leases recognized on a straight-line basis over the term of the lease. Rental expense for operating leases during the year ended December 31, 2018 was $29.3 million. ​ Other information related to leases for the year ended December 31, 2020 and 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands, except for lease term and discount rate) ​ December 31, 2020 ​ December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows for operating leases ​ $ 18,870 ​ ​ $ 24,140 ​ Financing cash flows for finance leases ​ ​ 490 ​ ​ ​ — ​ Operating cash flows from finance leases ​ ​ 31 ​ ​ ​ — ​ Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ROU assets obtained in exchange for lease liabilities ​ ​ 7,774 ​ ​ 4,808 ​ Finance Leases ​ ​ ​ ​ ​ ​ ​ ​ ROU assets obtained in exchange for lease liabilities ​ ​ 2,428 ​ ​ ​ — ​ ​ Additional information related to our operating leases for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ 18.83 ​ Weighted average discount rate ​ ​ 6.95 % ​ Additional information related to our finance leases for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ 3.59 ​ Weighted average discount rate ​ ​ 3.81 % ​ The following tables set forth supplemental balance sheet information related to operating and finance leases as of December 31, 2020 and December 31, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands) ​ December 31, 2020 ​ December 31, 2019 Operating Leases ​ ​ ​ ​ ​ ​ Right of use assets, net ​ $ 196,711 ​ $ 201,128 ​ ​ ​ ​ ​ ​ ​ Short-term lease liabilities ​ ​ 13,727 ​ ​ 10,709 Long-term lease liabilities ​ ​ 185,823 ​ ​ 188,149 Total operating lease obligation ​ $ 199,550 ​ $ 198,858 ​ ​ ​ ​ ​ ​ ​ Finance Leases ​ ​ ​ ​ ​ ​ Property and equipment, at cost ​ $ 2,428 ​ $ — Accumulated depreciation ​ ​ (248) ​ ​ — Total property and equipment, net ​ $ 2,180 ​ $ — ​ ​ ​ ​ ​ ​ ​ Short-term lease liabilities ​ $ 327 ​ $ — Long-term lease liabilities ​ ​ 1,609 ​ ​ — Total finance lease obligation ​ $ 1,936 ​ $ — ​ Maturities of noncancelable operating and finance lease liabilities under Topic 842 as of December 31, 2020 are summarized in the table below. ​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) ​ As of December 31, 2020 ​ ​ Finance Leases ​ Operating Leases 2021 ​ $ 397 ​ $ 26,859 2022 ​ ​ 651 ​ 22,326 2023 ​ ​ 651 ​ 22,225 2024 ​ ​ 384 ​ 20,473 2025 ​ ​ — ​ 18,388 Thereafter ​ ​ — ​ 261,746 Total ​ $ 2,083 ​ $ 372,017 Less: present value discount ​ ​ (147) ​ (172,467) Lease liability ​ $ 1,936 ​ $ 199,550 ​ ​ ​ Practical Expedients ​ We have elected the package of practical expedients for adoption of Topic 842 permitted under the transition guidance within the standard, which among other things allows us to carry forward historical lease classification, indirect costs and the original determination of whether or not a contract contained a lease. ​ We have elected the practical expedient to not separate a qualifying lease into its lease and non-lease components.

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2020
Business Segments
Business Segments	17. Business Segments We manage our operations on an individual park location basis, including operations from parks owned, managed and branded. Discrete financial information is maintained for each park and provided to our corporate management for review and as a basis for decision making. The primary performance measures used to allocate resources is Park EBITDA (defined as park-related operating earnings, excluding the impact of interest, taxes, depreciation, amortization and any other non-cash income or expenditures). Substantially all of our parks provide similar products and services through a similar process to the same class of customer through a consistent method. We also believe that the parks share common economic characteristics. Based on these factors, we have only one reportable segment - parks. The following table presents segment financial information and a reconciliation of net (loss) income to Park EBITDA. Park level expenses exclude all non-cash operating expenses, principally depreciation and amortization and all non-operating expenses. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) ​ 2020 ​ 2019 ​ 2018 Net (loss) income $ (382,092) $ 219,818 $ 316,003 Interest expense, net ​ 154,723 ​ 113,302 ​ 107,243 Income tax (benefit) expense ​ (140,967) ​ 91,942 ​ 95,855 Depreciation and amortization ​ 120,173 ​ 118,230 ​ 115,693 Corporate expenses (excluding stock-based compensation) ​ 47,732 ​ 54,301 ​ 48,679 Stock-based compensation ​ 19,530 ​ 13,274 ​ (46,684) Non-operating park level expense, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss on disposal of assets ​ 7,689 ​ 2,162 ​ 1,879 Loss on debt extinguishment, net ​ 6,106 ​ 6,484 ​ — Other expense, net ​ 24,993 ​ 2,542 ​ 3,508 Park EBITDA $ (142,113) $ 622,055 $ 642,176 ​ All of our owned or managed parks are located in the United States with the exception of two parks in Mexico and one park in Montreal, Canada. We also have revenue and expenses related to the development of Six Flags-branded parks outside of North America. The following information reflects our long-lived assets (which consists of property and equipment, intangible assets and right-of-use assets), revenues and (loss) income before income taxes by domestic and foreign categories as of or for the years ended December 31, 2020, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic Foreign Total As of or for the year ended December 31, 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,317,009 $ 134,805 $ 2,451,814 Revenues ​ 334,713 ​ 21,862 ​ 356,575 Loss before income taxes ​ (487,594) ​ (35,464) ​ (523,059) As of or for the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,347,578 $ 142,376 $ 2,489,954 Revenues ​ 1,370,367 ​ 117,216 ​ 1,487,583 Income before income taxes ​ 297,752 ​ 14,008 ​ 311,760 As of or for the year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,160,970 $ 101,359 $ 2,262,329 Revenues ​ 1,335,787 ​ 127,920 ​ 1,463,707 Income before income taxes ​ 383,875 ​ 27,983 ​ 411,858 ​

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information (Unaudited)
Quarterly Financial Information (Unaudited)	18. Quarterly Financial Information (Unaudited) Following is a summary of the unaudited interim results of operations for the years ended December 31, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ First ​ Second ​ Third ​ Fourth (Amounts in thousands) Quarter Quarter Quarter Quarter Total revenue $ 102,503 $ 19,143 $ 126,327 $ 108,602 (Loss) before income taxes ​ ​ (106,595) ​ ​ (171,911) ​ ​ (131,771) ​ ​ (112,782) Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ (84,546) ​ (136,894) ​ (116,172) ​ (85,768) Net (loss) income per weighted average common share outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic $ (1.00) $ (1.62) $ (1.37) $ (1.00) Diluted ​ (1.00) ​ (1.62) ​ (1.37) ​ (1.00) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ First ​ Second ​ Third ​ Fourth (Amounts in thousands) Quarter Quarter Quarter Quarter Total revenue $ 128,193 $ 477,210 $ 621,180 $ 261,000 (Loss) income before income taxes ​ ​ (93,789) ​ ​ 133,571 ​ ​ 261,835 ​ ​ 10,143 Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ (69,132) ​ 79,519 ​ 179,833 ​ (11,155) Net (loss) income per weighted average common share outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic $ (0.82) $ 0.94 $ 2.13 $ (0.13) Diluted ​ (0.82) ​ 0.94 ​ 2.11 ​ (0.13) ​ We operate a seasonal business. In particular, our theme park and waterpark operations contribute most of their annual revenue during the period from Memorial Day to Labor Day each year.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Basis of Presentation	The consolidated financial statements include our accounts and the accounts of our wholly owned subsidiaries. We also consolidate the partnerships that own Six Flags Over Texas ("SFOT") and Six Flags Over Georgia (including Six Flags White Water Atlanta) ("SFOG", and together with SFOT, the "Partnership Parks") as subsidiaries in our consolidated financial statements as we have determined that we have the power to direct the activities of those entities that most significantly impact the entities’ economic performance and we have the obligation to absorb losses and receive benefits from the entities that can be potentially significant to these entities. The equity interests owned by non-affiliated parties in the Partnership Parks are reflected in the accompanying consolidated balance sheets as redeemable noncontrolling interests. The portion of earnings or loss attributable to non-affiliated parties in the Partnership Parks is reflected as net income attributable to noncontrolling interests in the accompanying consolidated statements of operations. See Note 6 for further discussion. Intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our consolidated financial statements and accompanying notes. Actual results could differ from those estimates. We evaluate our estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which we believe to be reasonable under the circumstances. We adjust such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in these estimates resulting from continuing changes in the economic environment will be reflected in the financial statements in future periods.
Fair Value of Financial Instruments	Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement Fair Value Measurement ● Level 1: quoted prices in active markets for identical assets; ● Level 2: inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the instrument; and ● Level 3: inputs to the valuation methodology are unobservable for the asset or liability. The fair value of a financial instrument is the amount at which the instrument could be exchanged in a current transaction between willing parties. We use a market approach for our recurring fair value measurements, and we endeavor to use the best information available. Accordingly, valuation techniques that maximize the use of observable impacts are favored. We present the estimated fair values and classifications of our financial instruments in accordance with FASB Accounting Standards Consideration ("ASC") Topic 820, Fair Value Measurement. The following methods and assumptions were used to estimate the fair value of each class of financial instruments: ● The carrying values of cash and cash equivalents, accounts receivable, notes receivable, accounts payable and accrued liabilities approximate fair value because of the short maturity of these instruments. ● The measurement of the fair value of long-term debt is based on market prices that generally are observable for similar liabilities at commonly quoted intervals and is considered a Level 2 fair value measurement. Refer to Note 8 for additional information. ● The measurement of the fair value of derivative assets and liabilities is based on market prices that generally are observable for similar assets and liabilities at commonly quoted intervals and is considered a Level 2 fair value measurement. Derivative assets and liabilities that have maturity dates equal to or less than twelve months from the balance sheet date are included in prepaid expenses and other current assets and other accrued liabilities, respectively. Derivative assets and liabilities that have maturity dates greater than twelve months from the balance sheet date are included in deposits and other assets and other long-term liabilities, respectively. See Note 7 for additional information on our derivative instruments.
Cash Equivalents	Cash equivalents consists of short-term highly liquid investments with a remaining maturity as of the date of purchase of three months or less. For purposes of the consolidated statements of cash flows, we consider all highly liquid debt instruments with remaining maturities as of their date of purchase of three months or less to be cash equivalents. Cash equivalents were not significant as of December 31, 2020 and 2019.
Inventories	Inventories are stated at lower of weighted average cost or net realizable value and primarily consist of products purchased for resale, including merchandise, food and miscellaneous supplies. Products are removed from inventory at weighted average cost. We have recorded a $0.7 million and a $0.4 million allowance for slow moving inventory as of December 31, 2020 and 2019, respectively.
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets include $21.6 million and $22.9 million of spare parts inventory for existing rides and attractions as of December 31, 2020 and 2019. These items are expensed as the repair or maintenance of rides and attractions occur.
Advertising Costs	Production costs of commercials and programming are charged to operations in the year first aired. The costs of other advertising, promotion, and marketing programs are charged to operations when incurred with the exception of direct-response advertising which is charged to the period it will benefit. As of December 31, 2020 and 2019, we had $1.6 million and $1.8 million in prepaid advertising, respectively. The amounts capitalized are included in prepaid expenses. Advertising and promotions expense was $19.6 million, $69.5 million and $68.4 million for the years ended December 31, 2020, 2019 and 2018, respectively.
Debt Issuance Costs	We capitalize costs related to the issuance of debt. Debt issuance costs directly related to the Second Amended and Restated Revolving Loan are presented within other assets as debt issuance costs in our consolidated balance sheets. Debt issuance costs directly related to the Second Amended and Restated Term Loam B and our senior unsecured notes are presented within noncurrent liabilities as a reduction of long-term debt in our consolidated balance sheets. The amortization of such costs is recognized as interest expense using the interest method over the term of the respective debt issue. Amortization related to debt issuance costs was $6.5 million, $3.6 million and $4.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. See Note 8 for further discussion.
Property and Equipment	Property and equipment additions are recorded at cost and the carrying value is depreciated using the straight-line method over the estimated useful lives of the assets. Maintenance and repair costs that do not improve service potential or extend economic life are charged directly to expense as incurred, while betterments and renewals are generally capitalized as property and equipment. When an item is retired or otherwise disposed of, the cost and applicable accumulated depreciation are removed and the resulting gain or loss is recognized. See Note 4 for further detail of the components of our property and equipment. The estimated useful lives of the assets are as follows: ​ ​ ​ ​ Rides and attractions 5 - 25 years Land improvements ​ 10 - 15 years Buildings and improvements ​ Approximately 30 years Furniture and equipment ​ 5 - 10 years
Goodwill and Indefinite-Lived Intangible Assets	Goodwill and intangible assets with indefinite useful lives are tested for impairment annually in the fourth quarter, or more frequently if events or circumstances indicate that the assets might be impaired. We identify our reporting unit and determine the carrying value of the reporting unit by assigning the assets and liabilities, including the existing goodwill and intangible assets, to the reporting unit. We then determine the fair value of the reporting unit and compare it to the carrying amount of the reporting unit. All of our parks are operated in a similar manner and have comparable characteristics in that they produce and distribute similar services and products using similar processes, have similar types of customers, are subject to similar regulations and exhibit similar economic characteristics. As such, we are a single reporting unit. For each year, the fair value of the single reporting unit exceeded our carrying amount (provided that, we have one reporting unit at the same level for which Holdings common stock is traded, we believe our market capitalization is the best indicator of our reporting unit’s fair value). We perform a qualitative analysis on indefinite-lived intangible assets to determine if it is more likely than not that the fair value of the intangible asset was less than its carrying amount as a basis for determining whether it was necessary to perform a quantitative impairment test. The fair value of indefinite-lived intangible assets is generally determined based on a discounted cash flow analysis. An impairment loss occurs to the extent that the carrying value exceeds the fair value. For goodwill, if the fair value of the reporting unit were to be less than the carrying amount, an impairment loss would be recognized to the extent that the carrying amount of the reporting unit exceeds its fair value.
Valuation of Long-Lived Assets	We review long-lived assets, including finite-lived intangible assets subject to amortization, for impairment upon the occurrence of events or changes in circumstances that would indicate that the carrying value of the asset or group of assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset or group of assets to the future net cash flows expected to be generated by the asset or group of assets. If such assets are not considered to be fully recoverable, any impairment to be recognized is measured by the amount by which the carrying amount of the asset or group of assets exceeds its respective fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell.
Revenue Recognition	We account for revenue from contracts with customers based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We recognize revenue upon admission into our parks, provision of our services, or when products are delivered to our guests. Revenues are presented in the accompanying consolidated statements of operations net of sales taxes collected from our guests that are remitted or payable to government taxing authorities. For season passes, memberships in the initial twelve-month term and other multi-use admissions, we estimate a redemption rate based on historical experience and other factors and assumptions we believe to be customary and reasonable and recognize a pro-rata portion of the revenue as the guests visit our parks. Amounts owed or received for multi-use admissions in excess of redemptions are recognized in deferred revenue. In contrast to our season pass and other multi-use offerings (such as our all season dining pass program, which enables season passholders and members to eat meals and snacks any day they visit the park for one upfront payment) that expire at the end of each operating season, the membership program continues on a month-to-month basis after the initial twelve-month membership term and can be canceled any time after the initial term pursuant to the terms of the membership program. Guests enrolled in the membership program can visit our parks an unlimited number of times whenever the parks are open as long as the guest remains enrolled in the membership program. We review the estimated redemption rate on an ongoing basis and revise it as necessary throughout the year, including impact of changes to our season pass and memberships described above. For any bundled products with multiple performance obligations, revenue is allocated using the retail price of each distinct performance obligation and products that are not sold on a stand-alone basis are treated as residual. ​ In connection with the temporary closure of our parks due to COVID-19, we added one ​ As of December 31, 2020, deferred revenue was primarily comprised of (i) unredeemed season pass and all-season dining pass revenue, (ii) unredeemed portions of the membership program and member dining program that will be recognized in 2021, and (iii) pre-sold single-day admissions revenue for the 2020 operating season which now expire at the end of the 2021 season. ​ Certain contracts with customers, primarily memberships, may include bundled products with multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the observable retail prices charged to customers and use residual for any products not sold on a stand-alone basis. We generally expense (i) sales commissions when incurred, and (ii) certain costs to obtain a contract where the amortization period would have been one year or less. These costs are recognized in "Selling, general and administrative expenses." We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less or (ii) contracts for which we recognize revenue at the amount for which we have the right to invoice for services performed. For certain of our contracts that have an original expected length of one year or less, we use the practical expedient applicable to such contracts and do not consider the time value of money. We have entered into international agreements to assist a third party in the planning, design, development and operation of a Six Flags-branded park outside of North America. These agreements consist of a brand licensing agreement, project services agreement, and management services agreement. We treat these agreements as one contract because they were negotiated with a single commercial objective. We have identified three distinct promises within the agreement with the third-party partner as brand licensing, project services and management services. Each of these promises is its own performance obligation and distinct, as the third party could benefit from each service on its own with other readily available resources, and each service is separately identifiable from other services in the context of the contract. We recognize revenue under our international agreements over the relevant service period of each performance obligation based on its relative stand-alone selling price, as determined by our best estimate of selling price. We review the service period of each performance obligation on an ongoing basis and revise it as necessary throughout the year. Revisions to the relevant service periods of the performance obligations may result in revisions to revenue in future periods and are recognized in the period in which the change is identified.
Accounts Receivable, Net	Accounts receivable are reported at net realizable value and consist primarily of amounts due from guests for the sale of group outings and multi-use admission products, including the membership program. We are not exposed to a significant concentration of credit risk, however, based on the age of the receivables, our historical experience and other factors and assumptions we believe to be customary and reasonable, we do record an allowance for doubtful accounts. As of December 31, 2020 and 2019, we have recorded an allowance for doubtful accounts of $3.1 million and $8.3 million, respectively. The allowance for doubtful accounts is primarily comprised of estimated defaults under our membership plans.
Commitments and Contingencies	We are involved in various lawsuits and claims that arise in the normal course of business. Amounts associated with lawsuits or claims are reserved for matters in which it is believed that losses are probable and can be reasonably estimated. In addition to matters in which it is believed that losses are probable, disclosure is also provided for matters in which the likelihood of an unfavorable outcome is at least reasonably possible but for which a reasonable estimate of loss or range of loss is not possible. Legal fees are expensed as incurred. See Note 15 for further discussion.
Income Taxes	Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, including net operating loss and other tax carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. We have a valuation allowance of $128.2 million and $130.6 million as of December 31, 2020 and 2019, respectively, due to uncertainties related to our ability to utilize some of our deferred tax assets, primarily consisting of certain state net operating loss, foreign tax credits and other tax carryforwards, before they expire. The valuation allowance was based on our estimates of taxable income by jurisdiction in which we operate and the period over which our deferred tax assets were recoverable. For the foreseeable future, we project taxable income that will allow for the utilization of all of our federal net operating loss carryforwards. Our liability for income taxes is finalized as auditable tax years pass their respective statutes of limitations in the various jurisdictions in which we are subject to tax. However, these jurisdictions may audit prior years for which the statute of limitations is closed for the purpose of making an adjustment to our taxable income in a year for which the statute of limitations has not closed. Accordingly, taxing authorities of these jurisdictions may audit prior years of the group and its predecessors for the purpose of adjusting net operating loss carryforwards to years for which the statute of limitations has not closed. We classify interest and penalties attributable to income taxes as part of income tax expense. As of December 31, 2020 and 2019, we had no accrued interest and penalties liability. Because we do not permanently reinvest foreign earnings, United States deferred income taxes have been provided on unremitted foreign earnings to the extent that such foreign earnings are expected to be taxable upon repatriation. For global intangible low taxed income ("GILTI") under the Tax Cuts and Jobs Act, we have elected to account for GILTI as a component of tax expense in the period in which we are subject to the rules (the "period cost method"). See Note 11 for further discussion.
(Loss) Earnings Per Common Share	Basic (loss) earnings per common share is computed by dividing net (loss) income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per common share is computed by dividing net income attributable to Holdings’ common stockholders by the weighted average number of common shares outstanding during the period including the effect of all dilutive common stock equivalents using the treasury stock method. In periods for which there is a net loss, diluted loss per common share is equal to basic loss per common share, since the effect of including any common stock equivalents would be antidilutive.
Stock-Based Compensation	Pursuant to the Six Flags Entertainment Corporation Long-Term Incentive Plan (the "Long-Term Incentive Plan"), Holdings may grant stock options, stock appreciation rights, restricted stock, restricted stock units, unrestricted stock, deferred stock units, performance and cash-settled awards and dividend equivalents to select employees, officers, directors and consultants of Holdings and its affiliates. We recognize the fair value of each grant as compensation expense on a straight-line basis over the vesting period using the graded vesting terms of the respective grant. The fair value of stock option grants is estimated on the date of grant using the Black-Scholes option pricing valuation model. The fair value of stock, restricted stock units and restricted stock awards is the quoted market price of Holdings’ stock on the date of grant. See Note 10 for further discussion of stock-based compensation and related disclosures.
Comprehensive Income	Comprehensive (loss) income consists of net (loss) income, changes in the foreign currency translation adjustment, changes in the fair value of derivatives that are designated as hedges and changes in the net actuarial gains (losses) and amortization of prior service costs on our defined benefit retirement plan.
Redeemable Noncontrolling Interest	We record the carrying amount of our redeemable noncontrolling interests at their fair value at the date of issuance. We recognize the changes in their redemption value immediately as they occur and adjust the carrying value of these redeemable noncontrolling interests to equal the redemption value at the end of each reporting period, if greater than the redeemable noncontrolling interest carrying value. This method would view the end of the reporting period as if it were also the redemption date for the redeemable noncontrolling interests. We conduct an annual review to determine if the fair value of the redeemable units is less than the redemption amount. If the fair value of the redeemable units is less than the redemption amount, there would be a charge to earnings per share allocable to common stockholders. The redemption amount at the end of each reporting period did not exceed the fair value of the redeemable units.
Leases	We or certain of our subsidiaries are a lessee in various noncancelable operating and finance (formerly “capital”) leases, primarily for operating rights to amusement parks, land, office space, warehouses, office equipment and machinery. We account for leases in accordance with FASB ASC 842, Leases For both our operating and finance leases, the lease liability is initially and subsequently measured at the present value of the unpaid lease payments at the lease commencement date. Key estimates and judgments include how we determine (i) the discount rate used to discount the unpaid lease payments to present value, (ii) the lease term and (iii) the lease payments. Topic 842 requires a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate ("IBR"). Generally, we cannot determine the interest rate implicit in the lease and therefore we use the IBR as a discount rate for our leases. The IBR reflects the rate of interest we would pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The lease term for all of our leases includes the noncancelable period of the lease plus any additional periods covered by an option to extend the lease that are reasonably certain to be executed by us. Lease payments included in the measurement of the lease liability comprise fixed payments owed over the lease term, variable lease payments that depend on an index or rate, and the exercise price of an option to purchase the underlying asset if it is reasonably certain that we will exercise the option. The ROU asset is initially measured at cost, which comprises the initial amount of lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred, less any lease incentives received. For our operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, and adjusted for any prepaid or accrued lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the term of the operating lease. Variable lease payments associated with our leases are recognized upon the occurrence of the event, activity, or circumstance in the lease agreement on which those payments are assessed. Variable lease payments for operating leases are presented as operating expense in our consolidated statements of operations in the same line item as expense arising from fixed lease payments. Property taxes and insurance paid on behalf of our lessors is included within variable lease payments. Operating lease ROU assets net of accumulated amortization are presented as "Right-of-use operating leases, net" on the consolidated balance sheets. The current portion of operating lease liabilities is presented as "Short-term operating lease liabilities" and the long-term portion is presented separately as "Long-term operating lease liabilities" on the consolidated balance sheets. Finance lease ROU assets are presented within “Property and equipment, at cost” and the related lease amortization within “Accumulated depreciation” on our consolidated balance sheets. The current portion of the finance lease liabilities is presented as “Short-term lease liabilities” and the long-term portion is presented separately as “Long-term lease liabilities” on our consolidated balance sheets. We have elected not to recognize ROU assets and lease liabilities for short-term leases that have a lease term of 12 months or less. We recognize the lease payments associated with short-term leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with short-term leases are recognized and presented in the same manner as for all other leases. The ROU assets for operating leases may be periodically reduced by impairment losses. We use the long-lived assets impairment guidance to determine whether an ROU asset is impaired and if so, the amount of the impairment loss to recognize. We monitor for events or changes in circumstances that require a reassessment of one of our leases. When a reassessment results in the remeasurement of a lease liability, an adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the amount of the adjustment that would result in a negative ROU asset balance is recorded in our consolidated statements of operations.
Acquisition of Park Assets	On May 22, 2018, we entered into an asset purchase agreement with Premier Parks, LLC and its affiliates to acquire the lease rights to operate five parks owned by EPR Properties, LLC (the "five new parks"). We completed the transaction on June 1, 2018. In connection with the purchase agreement, we entered into operating leases with EPR Properties, LLC, under which we are the tenant. The five new parks were previously operated by Premier Parks, LLC of Oklahoma City and its affiliates. These acquisitions expanded our portfolio of parks in North America to twenty-five at the time of acquisition. The financial results of the five new parks since the acquisition date are included in our consolidated statements of operations. Assets acquired and liabilities assumed, consisting primarily of working capital, are reflected in our consolidated financial statements. We paid $19.1 million in cash to Premier Parks, LLC for the five new parks, which reflects the $23.0 million purchase price, less net working capital and other adjustments. We recorded $29.4 million of goodwill in connection with the acquisition, which is attributable to the excess of the purchase price over the net working capital liabilities we assumed.

Description of Business (Tables

Description of Business (Tables)	12 Months Ended
	Dec. 31, 2020
Description of Business
Schedule of Transformation Costs Breakout by Quarter	​ ​ ​ ​ ​ Transformation Costs Breakout ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2020 Amounts included in "Other expense, net" ​ ​ ​ Consultant costs ​ $ 20,460 Employee termination costs ​ ​ 4,362 Amounts included in "Loss on disposal of assets" ​ ​ ​ Ride / asset write-offs ​ ​ 9,754 Total transformation costs ​ $ 34,576

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Schedule of estimated useful lives of property and equipment	​ ​ ​ ​ Rides and attractions 5 - 25 years Land improvements ​ 10 - 15 years Buildings and improvements ​ Approximately 30 years Furniture and equipment ​ 5 - 10 years

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue
Schedule of revenues disaggregated by contract duration	The following tables present our revenues disaggregated by contract duration for the years ended December 31, 2020, 2019 and 2018, respectively. Long-term and short-term contracts consist of our contracts with customers with terms greater than one year and less than or equal to one year, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 28,627 ​ $ 2,431 ​ $ 20,762 ​ $ 51,820 Short-term contracts and other (a) ​ 174,019 ​ 123,875 ​ 6,861 ​ 304,755 Total revenues ​ $ 202,646 ​ $ 126,306 ​ $ 27,623 ​ $ 356,575 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 106,233 ​ $ 20,381 ​ $ 71,893 ​ $ 198,507 Short-term contracts and other (a) ​ 709,549 ​ 554,059 ​ 25,468 ​ 1,289,076 Total revenues ​ $ 815,782 ​ $ 574,440 ​ $ 97,361 ​ $ 1,487,583 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Sponsorship, ​ ​ ​ ​ ​ ​ Park Food, International ​ ​ ​ ​ ​ ​ ​ Merchandise Agreements and ​ ​ ​ (Amounts in thousands) Park Admissions and Other Accommodations Consolidated Long-term contracts ​ $ 115,612 ​ $ 25,383 ​ $ 71,589 ​ $ 212,584 Short-term contracts and other (a) ​ 694,452 ​ 528,144 ​ 28,527 ​ 1,251,123 Total revenues ​ $ 810,064 ​ $ 553,527 ​ $ 100,116 ​ $ 1,463,707 ​ (a) Other revenues primarily include sales of single-use tickets and short-term transactional sales for which we have the right to invoice.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property and Equipment
Summary of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Land ​ $ 219,453 ​ $ 221,616 Land improvements ​ 274,089 ​ 264,417 Buildings and improvements ​ 324,943 ​ 318,960 Rides and attractions ​ 1,207,029 ​ 1,213,543 Equipment and other ​ 383,176 ​ 326,747 Property and equipment, at cost ​ 2,408,690 ​ 2,345,283 Accumulated depreciation ​ (1,157,403) ​ (1,061,287) Property and equipment, net ​ $ 1,251,287 ​ $ 1,283,996

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets
Schedule of Intangible Assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 ​ Weighted-Average ​ ​ ​ ​ ​ ​ ​ Remaining ​ ​ ​ ​ ​ ​ ​ Amortization Period ​ Gross ​ Accumulated ​ Net (Amounts in thousands, except years) (Years) ​ Carrying Value ​ Amortization ​ Carrying Value Indefinite-lived intangible assets: ​ ​ ​ ​ ​ Trade names, trademarks and other ​ $ 344,075 ​ $ — ​ $ 344,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finite-lived intangible assets: ​ ​ ​ Third party licensing rights 5.5 ​ 361 ​ (238) ​ 123 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total intangible assets, net ​ $ 344,436 ​ $ (238) ​ $ 344,198 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Weighted-Average ​ ​ ​ ​ ​ ​ ​ Remaining ​ ​ ​ ​ ​ ​ ​ Amortization Period ​ Gross ​ Accumulated ​ Net (Amounts in thousands, except years) (Years) ​ Carrying Value ​ Amortization ​ Carrying Value Indefinite-lived intangible assets: ​ ​ ​ ​ ​ Trade names, trademarks and other ​ $ 344,075 ​ $ — ​ $ 344,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finite-lived intangible assets: ​ ​ ​ Third party licensing rights 0.5 ​ 24,361 ​ (23,224) ​ 1,137 Other — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total intangible assets, net ​ $ 368,436 ​ $ (23,224) ​ $ 345,212
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	​ ​ ​ ​ ​ (Amounts in thousands) ​ For the year ending December 31: ​ ​ 2021 ​ $ 22 2022 ​ ​ 22 2023 ​ ​ 22 2024 ​ ​ 22 2025 ​ ​ 22 2026 and thereafter ​ ​ 13 ​ ​ $ 123

Noncontrolling Interests, Par_2

Noncontrolling Interests, Partnership and Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interests, Partnerships and Joint Ventures
Schedule of changes in redeemable noncontrolling interests	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) SFOT SFOG Total Balance at December 31, 2018 ​ $ 243,756 ​ $ 281,515 ​ $ 525,271 Fresh start accounting fair market value adjustment for purchased units ​ ​ (45) ​ ​ — ​ ​ (45) Purchases of redeemable units ​ ​ (217) ​ ​ — ​ ​ (217) Change in redemption value of partnership units ​ ​ 3,250 ​ ​ 999 ​ ​ 4,249 Net income attributable to noncontrolling interests ​ ​ 20,452 ​ ​ 20,301 ​ ​ 40,753 Distributions to noncontrolling interests ​ ​ (20,452) ​ ​ (20,301) ​ ​ (40,753) Balance at December 31, 2019 ​ ​ 246,744 ​ ​ 282,514 ​ ​ 529,258 Fresh start accounting fair market value adjustment for purchased units ​ ​ (720) ​ ​ (204) ​ ​ (924) Purchases of redeemable units ​ ​ (3,440) ​ ​ (1,536) ​ ​ (4,976) Change in redemption value of partnership units ​ ​ 11 ​ ​ 7 ​ ​ 18 Net income attributable to noncontrolling interests ​ ​ 20,634 ​ ​ 20,654 ​ ​ 41,288 Distributions to noncontrolling interests ​ ​ (20,634) ​ ​ (20,654) ​ ​ (41,288) Balance at December 31, 2020 ​ $ 242,595 ​ $ 280,781 ​ $ 523,376

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Financial Instruments
Schedule of derivative instruments recorded at fair value	Derivative assets recorded at fair value in our consolidated balance sheets as of December 31, 2020 and 2019, respectively, consisted of the following: ​ ​ ​ ​ ​ ​ ​ Derivative Assets (Amounts in thousands) December 31, 2020 December 31, 2019 Derivatives Designated as Cash Flow Hedges ​ ​ ​ ​ ​ Interest Rate Swap Agreements — Current $ — $ 485 Interest Rate Swap Agreements — Noncurrent ​ — ​ ​ 1,440 Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ Interest Rate Swap Agreements - Current 877 ​ — Interest Rate Swap Agreements - Noncurrent ​ 585 ​ ​ — ​ $ 1,462 $ 1,925 ​ Derivative liabilities recorded at fair value in our consolidated balance sheets as of December 31, 2020 and December 31, 2019, respectively, consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivative Liabilities (Amounts in thousands) ​ December 31, 2020 December 31, 2019 Derivatives Designated as Cash Flow Hedges ​ ​ ​ ​ ​ ​ Interest Rate Swap Agreements — Current ​ $ (5,251) $ (788) Interest Rate Swap Agreements — Noncurrent ​ ​ (11,633) ​ ​ (2,667) Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ Interest Rate Swap Agreements - Current ​ (4,875) ​ — Interest Rate Swap Agreements - Noncurrent ​ ​ (9,032) ​ ​ — ​ ​ $ (30,791) $ (3,455)
Schedule of gains and losses before taxes on derivatives designated as cash flow hedges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss ​ Loss Reclassified from ​ ​ Recognized in AOCL ​ AOCL into Operations (Amounts in thousands) 2020 2019 2018 2020 2019 2018 Interest Rate Swap Agreements ​ $ (33,902) ​ $ (484) $ — $ (3,685) ​ $ 1,046 $ — Total $ (33,902) ​ $ (484) $ — $ (3,685) ​ $ 1,046 $ —

Long-Term Indebtedness (Tables)

Long-Term Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2020
Long-Term Indebtedness
Schedule of long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ As of (Amounts in thousands) December 31, 2020 December 31, 2019 Second Amended and Restated Term Loan B $ 479,000 $ 796,000 2024 Notes ​ 949,490 ​ 1,000,000 2025 Notes ​ ​ 725,000 ​ ​ — 2027 Notes ​ 500,000 ​ 500,000 Net discount ​ (4,357) ​ (6,535) Deferred financing costs ​ (26,492) ​ (14,581) Total debt ​ $ 2,622,641 ​ $ 2,274,884 Less current portion of long-term debt ​ — ​ (8,000) Total long-term debt ​ $ 2,622,641 ​ $ 2,266,884
Schedule of annual maturities of long-term debt	As of December 31, 2020, annual maturities of long-term debt, assuming no acceleration of maturities, were as follows: ​ ​ ​ ​ (Amounts in thousands) ​ For the year ending December 31: ​ ​ 2021 ​ ​ — 2022 ​ ​ — 2023 ​ ​ — 2024 ​ ​ 949,490 2025 ​ ​ 725,000 2026 and thereafter ​ ​ 979,000 ​ ​ $ 2,653,490

Selling, General and Administ_2

Selling, General and Administrative Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Selling, General and Administrative Expenses
Summary of selling, general and administrative expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Park ​ $ 80,027 ​ $ 131,619 ​ $ 129,335 Corporate ​ 67,268 ​ 67,575 ​ 2,833 Total selling, general and administrative expenses ​ $ 147,295 ​ $ 199,194 ​ $ 132,168

Stock Benefit Plans (Tables)

Stock Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Stock Benefit Plans
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 December 31, 2019 December 31, 2018 ​ ​ CEO Employees CEO Employees CEO Employees ​ Risk-free interest rate — ​ 1.60 % 1.59 % 1.42 % 2.52 % 2.67 % Expected life (in years) — 3.67 3.67 3.67 3.85 3.68 ​ Expected volatility — ​ 28.38 % 28.62 % 26.96 % 23.20 % 22.51 % Expected dividend yield — ​ 7.18 % 6.47 % 6.12 % 4.67 % 4.54 %
Schedule of Share-based Compensation, Stock Options, Activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Avg. ​ Weighted Avg. ​ ​ ​ ​ ​ ​ Exercise Price ​ Remaining ​ Aggregate ​ ​ ​ ​ Per Share ​ Contractual ​ Intrinsic Value (Amounts in thousands, expect per share and term data) ​ Shares ​ ($) ​ Term ​ ($) Balance at December 31, 2019 ​ 6,408 ​ $ 52.42 ​ ​ ​ Granted ​ 9 ​ $ 44.73 ​ ​ ​ Exercised ​ (127) ​ $ 17.64 ​ ​ ​ Canceled or exchanged ​ (1,061) ​ $ 53.50 ​ ​ ​ Forfeited ​ (432) ​ $ 59.85 ​ ​ ​ Expired ​ — ​ $ — ​ ​ ​ Balance at December 31, 2020 ​ 4,797 ​ $ 52.42 ​ 6.27 ​ $ 2,569 Vested and expected to vest at December 31, 2020 ​ 4,679 ​ $ 52.23 ​ 6.22 ​ $ 2,569 Options exercisable at December 31, 2020 ​ 2,993 ​ $ 49.30 ​ 5.08 ​ $ 2,569
Schedule of Share-based Payment Award, Stock Options, Weighted-Average Information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands, expect per share data) 2020 2019 2018 Weighted average grant date fair value per share of options granted ​ $ 4.85 ​ $ 6.38 ​ $ 8.01 Total intrinsic value of options exercised ​ $ 1,275 ​ $ 7,130 ​ $ 31,822 Total fair value of vested options ​ $ 7,369 ​ $ 10,253 ​ $ 8,446 Total cash received from the exercise of stock options ​ $ 2,235 ​ $ 17,495 ​ $ 41,658
Schedule of Nonvested Share Activity	The following table summarizes stock, restricted stock and restricted stock unit activity for the year ended December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average Grant ​ ​ ​ ​ ​ Date Fair Value ​ ​ ​ ​ ​ Per Share (Amounts in thousands, except per share amounts ​ Shares ​ ​ ($) Non-vested balance at December 31, 2019 ​ 62 ​ $ 48.29 Granted ​ 1,569 ​ $ 18.86 Vested ​ (50) ​ $ 40.19 Forfeited ​ (121) ​ $ 19.01 Canceled ​ — ​ $ — Non-vested balance at December 31, 2020 ​ 1,460 ​ $ 19.37
Schedule of Share-based Payment Award, Other than Stock Options, Weighted-Average Information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands, expect per share data) 2020 2019 2018 Weighted average grant date fair value per share of stock awards granted ​ $ 18.86 ​ $ 48.29 ​ $ 63.80 Total grant date fair value of stock awards granted ​ $ 29,597 ​ $ 3,007 ​ $ 4,185 Total fair value of vested stock awards ​ $ 2,011 ​ $ 1,027 ​ $ 3,888
Schedule of stock-based compensation expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 ​ 2019 ​ 2018 Long-Term Incentive Plan ​ ​ ​ ​ ​ Options and other $ 19,078 ​ $ 13,037 ​ $ 15,543 Performance awards — ​ — ​ (62,512) Employee Stock Purchase Plan 452 ​ 237 ​ 285 Total Stock-Based Compensation $ 19,530 ​ $ 13,274 ​ $ (46,684)

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes
Schedule of Income before Income Tax, Domestic and Foreign	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Domestic ​ $ (487,594) ​ $ 297,752 ​ $ 383,875 Foreign ​ (35,464) ​ 14,008 ​ 27,983 (Loss) income before income taxes ​ $ (523,059) ​ $ 311,760 ​ $ 411,858
Schedule of Components of Income Tax Expense (Benefit)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) Current Deferred Total 2020: ​ ​ ​ ​ ​ ​ U.S. federal ​ $ (3,530) ​ $ (99,976) ​ $ (103,506) Foreign ​ — ​ (7,642) ​ (7,642) State and local ​ (3,239) ​ (26,580) ​ (29,819) Income tax (benefit) expense ​ $ (6,769) ​ $ (134,199) ​ $ (140,967) 2019: ​ ​ ​ U.S. federal ​ $ (2,960) ​ $ 67,975 ​ $ 65,015 Foreign ​ 5,812 ​ 1,169 ​ 6,981 State and local ​ 10,704 ​ 9,242 ​ 19,946 Income tax expense ​ $ 13,556 ​ $ 78,386 ​ $ 91,942 2018: ​ ​ ​ U.S. federal ​ $ (58) ​ $ 65,976 ​ $ 65,918 Foreign ​ 11,752 ​ 626 ​ 12,378 State and local ​ 11,268 ​ 6,291 ​ 17,559 Income tax expense ​ $ 22,962 ​ $ 72,893 ​ $ 95,855
Schedule of Effective Income Tax Rate Reconciliation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 ​ 2018 Computed "expected" federal income tax (benefit) expense ​ $ (109,842) ​ $ 65,470 ​ $ 86,490 Effect of noncontrolling interest income distribution ​ (8,671) ​ (8,558) ​ (8,401) Change in valuation allowance ​ (2,482) ​ 15,469 ​ 1,663 Effect of state and local income taxes, net of federal tax benefit ​ (14,356) ​ 18,622 ​ 12,980 Deductible compensation in excess of book ​ 773 ​ (2,029) ​ (5,392) Nondeductible compensation ​ 951 ​ 635 ​ 1,167 Effect of foreign income taxes ​ (4,072) ​ 2,084 ​ 4,544 Effect of foreign earnings earned and remitted in the same year ​ — ​ (302) ​ 2,317 Effect of foreign tax credits ​ (528) ​ (407) ​ (996) Other, net ​ (2,740) ​ 958 ​ 1,483 Income tax (benefit) expense ​ $ (140,967) ​ $ 91,942 ​ $ 95,855
Schedule of Deferred Tax Assets and Liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Deferred tax assets ​ $ 326,023 ​ $ 191,349 Less: Valuation allowance ​ 128,159 ​ 130,641 Net deferred tax assets ​ 197,864 ​ 60,708 Deferred tax liabilities ​ 299,695 ​ 307,829 Net deferred tax liability ​ $ 101,831 ​ $ 247,121 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, (Amounts in thousands) 2020 2019 Deferred tax assets: ​ ​ Federal net operating loss carryforwards ​ $ 115,168 ​ $ 12,615 State net operating loss carryforwards ​ 118,063 ​ 107,303 Deferred compensation ​ 9,307 ​ 8,240 Foreign tax credits ​ 21,367 ​ 20,469 Alternative minimum tax credits ​ — ​ 3,296 Accrued insurance, pension liability and other ​ 62,118 ​ 39,426 Total deferred tax assets ​ $ 326,023 ​ $ 191,349 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ Property and equipment ​ $ 220,927 ​ $ 226,872 Intangible assets and other ​ 78,768 ​ 80,957 Total deferred tax liabilities ​ $ 299,695 ​ $ 307,829

Preferred Stock, Common Stock_2

Preferred Stock, Common Stock and Other Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Preferred Stock, Common Stock and Other Stockholders' Equity
Schedule of quarterly cash dividends per share of common stock declared and paid	​ ​ ​ ​ ​ ​ ​ Dividends ​ ​ Paid ​ Per Share 2020: ​ ​ First Quarter ​ $ 0.25 2019: ​ Fourth Quarter ​ $ 0.83 Third Quarter ​ $ 0.82 Second Quarter ​ $ 0.82 First Quarter ​ $ 0.82 2018: ​ Fourth Quarter ​ $ 0.82 Third Quarter ​ $ 0.78 Second Quarter ​ $ 0.78 First Quarter ​ $ 0.78
Schedule of components of AOCI	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other ​ ​ Translation ​ Cash Flow ​ Defined Benefit ​ Income ​ Comprehensive (Amounts in thousands) Adjustment Hedges Plans Taxes Loss Balance as of December 31, 2017 ​ $ (28,822) ​ $ — ​ $ (41,959) ​ $ 6,900 ​ $ (63,881) Net current period change ​ 1,470 ​ — ​ 167 ​ (351) ​ 1,286 Amounts reclassified from AOCL ​ — ​ — ​ 721 ​ (185) ​ 536 Effects of Adoption of ASU 2018-02 ​ ​ — ​ ​ — ​ ​ — ​ ​ (9,439) ​ ​ (9,439) Balance as of December 31, 2018 ​ $ (27,352) ​ $ — ​ $ (41,071) ​ $ (3,075) ​ $ (71,498) Net current period change ​ 5,168 ​ (484) ​ (9,006) ​ 1,283 ​ (3,039) Amounts reclassified from AOCL ​ ​ — ​ ​ (1,046) ​ ​ 795 ​ ​ 78 ​ ​ (173) Balances at December 31, 2019 ​ $ (22,184) ​ $ (1,530) ​ $ (49,282) ​ $ (1,714) ​ $ (74,710) Net current period change ​ (5,228) ​ (33,902) ​ (9,345) ​ 11,968 ​ (36,507) Amounts reclassified from AOCL ​ — ​ 3,685 ​ 985 ​ (1,165) ​ 3,505 Amounts reclassified due to de-designation ​ ​ — ​ ​ 14,928 ​ ​ — ​ ​ (3,720) ​ ​ 11,208 Balances at December 31, 2020 ​ $ (27,412) ​ $ (16,819) ​ $ (57,642) ​ $ 5,369 ​ $ (96,504)
Schedule of reclassifications out of accumulated other comprehensive income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of Reclassification from AOCL ​ ​ ​ Year Ended December 31, Component of AOCL Location of Reclassification into Income 2020 ​ 2019 ​ 2018 Amortization of loss on interest rate hedge Interest expense $ 3,685 ​ $ (1,046) ​ $ — ​ Income tax benefit (917) ​ 276 ​ — ​ Net of tax $ 2,768 ​ $ (770) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of deferred actuarial loss and prior service cost Operating expenses $ 985 ​ $ 795 ​ $ 721 ​ Income tax expense (248) ​ (198) ​ (185) ​ Net of tax $ 737 ​ $ 597 ​ $ 536 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications $ 3,505 ​ $ (173) ​ $ 536

Pension Benefits (Tables)

Pension Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Pension Benefits
Schedule of changes in benefit plan obligation and fair value of plan assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Change in benefit obligation: ​ ​ ​ Beginning balance ​ $ 221,458 ​ $ 201,752 ​ $ 218,746 Interest cost ​ 6,431 ​ 7,993 ​ 7,386 Actuarial loss (gain) ​ 18,243 ​ 25,632 ​ (16,324) Benefits paid ​ (9,006) ​ (13,919) ​ (8,056) Benefit obligation at end of period ​ $ 237,126 ​ $ 221,458 ​ $ 201,752 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in fair value of plan assets: ​ ​ ​ Beginning balance ​ $ 205,463 ​ $ 184,758 ​ $ 190,534 Actual return on assets ​ 21,987 ​ 29,815 ​ (2,497) Employer contributions ​ 1,500 ​ 6,000 ​ 6,000 Administrative fees ​ (9,006) ​ (13,918) ​ (1,223) Benefits paid ​ (1,171) ​ (1,192) ​ (8,056) Fair value of plan assets at end of period ​ $ 218,773 ​ $ 205,463 ​ $ 184,758
Schedule of weighted average assumptions used to determine benefit obligations and net cost	​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Discount rate 2.20 % 3.00 % Rate of compensation increase N/A N/A ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Discount rate ​ 3.00 % 4.05 % 3.45 % Rate of compensation increase ​ N/A N/A N/A ​ Expected return on plan assets ​ 6.50 % 7.25 % 7.25 % Corridor ​ 10.00 % 10.00 % 10.00 % Average future life expectancy (in years) ​ 25.70 26.87 27.77 ​
Schedule of components of net periodic benefit cost and amounts recognized in other comprehensive income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) 2020 2019 2018 Net periodic benefit cost: ​ ​ ​ Service cost $ 1,200 ​ $ 1,300 ​ $ 1,300 Interest cost 6,431 ​ 7,993 ​ 7,386 Expected return on plan assets (13,119) ​ (13,296) ​ (13,737) Amortization of net actuarial loss 985 ​ 795 ​ 721 Total net periodic benefit $ (4,503) ​ $ (3,208) ​ $ (4,330) ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income: ​ ​ Current year actuarial (gain) loss $ (9,345) ​ $ (9,006) ​ $ 167 Recognized net actuarial loss 985 ​ 795 ​ 721 Total other comprehensive (gain) loss $ (8,360) ​ $ (8,211) ​ $ 888
Schedule of fair value of plan assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements as of December 31, 2020 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs (Amounts in thousands) ​ Total ​ (Level 1) ​ (Level 2) ​ (Level 3) ASSET CATEGORY: ​ ​ ​ ​ Equity Securities: ​ ​ ​ ​ Large-Cap Disciplined Equity (a) ​ $ 8,065 ​ $ 8,065 ​ $ — ​ $ — International Equity (b) ​ 42,178 ​ 42,178 ​ — ​ — Fixed Income: ​ ​ ​ ​ ​ Long Duration Fixed Income (c) ​ 138,399 ​ 138,399 ​ — ​ — Alternatives: ​ ​ ​ ​ Other Investments (f) ​ 30,131 ​ — ​ — ​ — Fair Value of Plan Assets ​ $ 218,773 ​ $ 188,642 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements as of December 31, 2019 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs (Amounts in thousands) ​ Total ​ (Level 1) ​ (Level 2) ​ (Level 3) ASSET CATEGORY: ​ ​ ​ ​ Equity Securities: ​ ​ ​ ​ Large-Cap Disciplined Equity (a) ​ $ 6,844 ​ $ 6,844 ​ $ — ​ $ — International Equity (b) ​ 35,962 ​ 35,962 ​ — ​ — Fixed Income: ​ ​ ​ ​ Long Duration Fixed Income (c) ​ 133,592 ​ 133,592 ​ — ​ — High Yield (d) ​ — ​ — ​ — ​ — Emerging Markets Debt (e) ​ — ​ — ​ — ​ — Alternatives: ​ ​ ​ ​ Other Investments (f) ​ 29,065 ​ — ​ — ​ — Fair Value of Plan Assets ​ $ 205,463 ​ $ 176,398 ​ $ — ​ $ — (a) These categories are comprised of mutual funds actively traded on the registered exchanges or over the counter markets. The mutual funds are invested in equity securities of U.S. issuers. (b) This category consists of mutual funds invested primarily in equity securities (common stocks, securities that are convertible into common stocks, preferred stocks, warrants and rights to subscribe to common stocks) of non-U.S. issuers purchased in foreign markets. The mutual funds are actively traded on U.S. or foreign registered exchanges, or the over-the-counter markets. (c) The assets are comprised of U.S. Treasury Separate Trading of Registered Interest and Principal of Securities ("U.S. Treasury STRIPS") and mutual funds which are actively traded on the registered exchanges. The mutual funds are invested primarily in high quality government and corporate fixed income securities, as well as synthetic instruments or derivatives having economic characteristics similar to fixed income securities. (d) The high yield portion of the fixed income portfolio consists of mutual funds invested primarily in fixed income securities that are rated below investment grade. The mutual funds are actively traded on the registered exchanges. (e) The emerging debt portion of the portfolio consists of mutual funds primarily invested in the debt securities of government, government-related and corporate issuers in emerging market countries and of entities organized to restructure outstanding debt of such issuers. The mutual funds are actively traded on the registered exchanges. (f) Common/collective trust investments that are measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the total fair value of plan assets. The Company has participant redemptions restricted to the last business day of the quarter, with either a 65 or 90 day period redemption notice.
Summary of expected employer contributions and future benefit payments	​ ​ ​ ​ ​ (Amounts in thousands) ​ ​ Expected contributions to plan trusts ​ 2021 ​ $ — Total expected contributions ​ $ — ​ ​ ​ ​ Expected benefit payments: ​ 2021 ​ $ 10,578 2022 ​ 11,072 2023 ​ 11,407 2024 ​ 11,709 2025 ​ 11,958 2026 through 2030 ​ 60,744 Total expected benefit payments ​ $ 117,468

(Loss) Earnings Per Common Sh_2

(Loss) Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
(Loss) Earnings Per Common Share
Schedule of (loss) earnings per common share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, (Amounts in thousands, except per share amounts) 2020 2019 2018 Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ $ (423,380) ​ $ 179,065 ​ $ 275,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding—basic ​ 84,800 ​ 84,348 ​ 84,100 Effect of dilutive stock options and restricted stock units ​ — ​ 620 ​ 1,345 Weighted-average common shares outstanding—diluted ​ 84,800 ​ 84,968 ​ 85,445 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Loss) earnings per share—basic ​ $ (4.99) ​ $ 2.12 ​ $ 3.28 (Loss) earnings per share—diluted ​ $ (4.99) ​ $ 2.11 ​ $ 3.23

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases
Schedule of components of lease cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands) ​ December 31, 2020 December 31, 2019 Finance Lease Expense ​ ​ ​ ​ ​ ​ Amortization of ROU assets ​ $ 248 ​ $ — Interest on lease liabilities ​ ​ 31 ​ ​ — Operating lease cost ​ ​ 24,166 ​ 24,890 Short-term lease cost ​ ​ 5,804 ​ ​ 6,925 Variable lease cost ​ ​ 4,816 ​ ​ 5,979 Total lease cost ​ $ 35,065 ​ $ 37,794
Schedule of other information related to leases	​ Other information related to leases for the year ended December 31, 2020 and 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands, except for lease term and discount rate) ​ December 31, 2020 ​ December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows for operating leases ​ $ 18,870 ​ ​ $ 24,140 ​ Financing cash flows for finance leases ​ ​ 490 ​ ​ ​ — ​ Operating cash flows from finance leases ​ ​ 31 ​ ​ ​ — ​ Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ROU assets obtained in exchange for lease liabilities ​ ​ 7,774 ​ ​ 4,808 ​ Finance Leases ​ ​ ​ ​ ​ ​ ​ ​ ROU assets obtained in exchange for lease liabilities ​ ​ 2,428 ​ ​ ​ — ​ ​ Additional information related to our operating leases for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ 18.83 ​ Weighted average discount rate ​ ​ 6.95 % ​ Additional information related to our finance leases for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ 3.59 ​ Weighted average discount rate ​ ​ 3.81 %
Schedule of supplemental balance sheet information of leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended (Amounts in thousands) ​ December 31, 2020 ​ December 31, 2019 Operating Leases ​ ​ ​ ​ ​ ​ Right of use assets, net ​ $ 196,711 ​ $ 201,128 ​ ​ ​ ​ ​ ​ ​ Short-term lease liabilities ​ ​ 13,727 ​ ​ 10,709 Long-term lease liabilities ​ ​ 185,823 ​ ​ 188,149 Total operating lease obligation ​ $ 199,550 ​ $ 198,858 ​ ​ ​ ​ ​ ​ ​ Finance Leases ​ ​ ​ ​ ​ ​ Property and equipment, at cost ​ $ 2,428 ​ $ — Accumulated depreciation ​ ​ (248) ​ ​ — Total property and equipment, net ​ $ 2,180 ​ $ — ​ ​ ​ ​ ​ ​ ​ Short-term lease liabilities ​ $ 327 ​ $ — Long-term lease liabilities ​ ​ 1,609 ​ ​ — Total finance lease obligation ​ $ 1,936 ​ $ —
Schedule of maturities of noncancelable operating lease liabilities	​ ​ ​ ​ ​ ​ ​ ​ (Amounts in thousands) ​ As of December 31, 2020 ​ ​ Finance Leases ​ Operating Leases 2021 ​ $ 397 ​ $ 26,859 2022 ​ ​ 651 ​ 22,326 2023 ​ ​ 651 ​ 22,225 2024 ​ ​ 384 ​ 20,473 2025 ​ ​ — ​ 18,388 Thereafter ​ ​ — ​ 261,746 Total ​ $ 2,083 ​ $ 372,017 Less: present value discount ​ ​ (147) ​ (172,467) Lease liability ​ $ 1,936 ​ $ 199,550

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2020
Business Segments
Schedule of segment financial information and a reconciliation of net income to Park EBITDA	The following table presents segment financial information and a reconciliation of net (loss) income to Park EBITDA. Park level expenses exclude all non-cash operating expenses, principally depreciation and amortization and all non-operating expenses. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (Amounts in thousands) ​ 2020 ​ 2019 ​ 2018 Net (loss) income $ (382,092) $ 219,818 $ 316,003 Interest expense, net ​ 154,723 ​ 113,302 ​ 107,243 Income tax (benefit) expense ​ (140,967) ​ 91,942 ​ 95,855 Depreciation and amortization ​ 120,173 ​ 118,230 ​ 115,693 Corporate expenses (excluding stock-based compensation) ​ 47,732 ​ 54,301 ​ 48,679 Stock-based compensation ​ 19,530 ​ 13,274 ​ (46,684) Non-operating park level expense, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss on disposal of assets ​ 7,689 ​ 2,162 ​ 1,879 Loss on debt extinguishment, net ​ 6,106 ​ 6,484 ​ — Other expense, net ​ 24,993 ​ 2,542 ​ 3,508 Park EBITDA $ (142,113) $ 622,055 $ 642,176
Schedule of information reflecting long-lived assets, revenues and income before income taxes by domestic and foreign categories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Domestic Foreign Total As of or for the year ended December 31, 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,317,009 $ 134,805 $ 2,451,814 Revenues ​ 334,713 ​ 21,862 ​ 356,575 Loss before income taxes ​ (487,594) ​ (35,464) ​ (523,059) As of or for the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,347,578 $ 142,376 $ 2,489,954 Revenues ​ 1,370,367 ​ 117,216 ​ 1,487,583 Income before income taxes ​ 297,752 ​ 14,008 ​ 311,760 As of or for the year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-lived assets $ 2,160,970 $ 101,359 $ 2,262,329 Revenues ​ 1,335,787 ​ 127,920 ​ 1,463,707 Income before income taxes ​ 383,875 ​ 27,983 ​ 411,858

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information (Unaudited)
Quarterly Financial Information (Unaudited)	Following is a summary of the unaudited interim results of operations for the years ended December 31, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ First ​ Second ​ Third ​ Fourth (Amounts in thousands) Quarter Quarter Quarter Quarter Total revenue $ 102,503 $ 19,143 $ 126,327 $ 108,602 (Loss) before income taxes ​ ​ (106,595) ​ ​ (171,911) ​ ​ (131,771) ​ ​ (112,782) Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ (84,546) ​ (136,894) ​ (116,172) ​ (85,768) Net (loss) income per weighted average common share outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic $ (1.00) $ (1.62) $ (1.37) $ (1.00) Diluted ​ (1.00) ​ (1.62) ​ (1.37) ​ (1.00) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ First ​ Second ​ Third ​ Fourth (Amounts in thousands) Quarter Quarter Quarter Quarter Total revenue $ 128,193 $ 477,210 $ 621,180 $ 261,000 (Loss) income before income taxes ​ ​ (93,789) ​ ​ 133,571 ​ ​ 261,835 ​ ​ 10,143 Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders ​ (69,132) ​ 79,519 ​ 179,833 ​ (11,155) Net (loss) income per weighted average common share outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic $ (0.82) $ 0.94 $ 2.13 $ (0.13) Diluted ​ (0.82) ​ 0.94 ​ 2.11 ​ (0.13) ​

Description of Business (Detail

Description of Business (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)itempayment	Apr. 30, 2020USD ($)	Apr. 22, 2020USD ($)	Mar. 31, 2020USD ($)	Apr. 17, 2019USD ($)
Summary of Significant Accounting Policies
Number of parks owned or operated	26
Period of operation of theme parks by the former SFEC under Six Flags name (in years)	40 years
Number of parks branded as "Six Flags" parks	22
Number of reporting units	1
Number of upfront payments | payment	1
Initial membership term	12 months
COVID 19 Considerations
Percentage of base salaries reduced for full-time salaried employees	25.00%
Number of parks with suspended operations due to pandemic	20
Transformation Initiative
Total transformation costs | $	$ 34,576
Number of revenue initiatives	5
Number of cost initiatives	3
Number of satellite offices closed	2
Other expense (income). net
Transformation Initiative
Consultant costs | $	$ 20,460
Employee termination costs | $	4,362
Loss on disposal of assets
Transformation Initiative
Ride / asset write-offs | $	$ 9,754
Second Amended and Restated Term Loan B
COVID 19 Considerations
Incremental borrowing capacity | $		$ 131,000
Maximum borrowing capacity | $		481,000		$ 350,000	$ 800,000
Senior Unsecured 2025 Notes
COVID 19 Considerations
Debt instrument, face amount | $		$ 725,000
Interest rate, stated percentage		7.00%
Senior Unsecured 2025 Notes | Six Flags Theme Parks Inc.
COVID 19 Considerations
Debt instrument, face amount | $			$ 725,000
Interest rate, stated percentage			7.00%
United States
Summary of Significant Accounting Policies
Number of parks owned or operated	23
Mexico
Summary of Significant Accounting Policies
Number of parks owned or operated	2
Canada
Summary of Significant Accounting Policies
Number of parks owned or operated	1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details)	Apr. 22, 2020USD ($)	Jun. 01, 2018USD ($)item	Apr. 01, 1998USD ($)	Dec. 31, 2020USD ($)paymentitem	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Apr. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Aug. 31, 2019USD ($)item	Jun. 30, 2019USD ($)item	May 22, 2018item
Summary of Significant Accounting Policies
Valuation allowance for slow moving inventory				$ 700,000	$ 400,000
Spare parts inventory for existing rides and attractions included in prepaid expenses and other current assets				21,600,000	22,900,000
Prepaid advertising				1,600,000	1,800,000
Advertising and promotions expense				19,600,000	69,500,000	$ 68,400,000
Amortization of debt issuance costs				$ 6,535,000	3,563,000	3,979,000
Number of reporting units | item				1
Number of upfront payments | payment				1
Initial membership term				12 months
Time period added to membership privileges				1 month
Number of contracts in a typical international agreement | item				1
Number of distinct promises within a typical international agreement | item				3
Repayments of Debt				$ 526,510,000	802,750,000	$ 274,000,000
Allowance for doubtful accounts				3,100,000	8,300,000
Valuation allowance				128,159,000	130,641,000
Accrued interest and penalties, income taxes				$ 0	0
Number of leased parks acquired | item		25
Number of parks owned or operated | item				26
Payments to acquire businesses			$ 976,000,000
Goodwill				$ 659,618,000	$ 659,618,000
Premier Parks, LLC
Summary of Significant Accounting Policies
Number of leased parks acquired | item		5									5
Payments to acquire businesses		$ 19,100,000
Consideration transferred		23,000,000
Goodwill		$ 29,400,000
Interest Rate Swap
Summary of Significant Accounting Policies
Notional amount										$ 300,000,000
Modified June 2019 Swap Agreement
Summary of Significant Accounting Policies
Notional amount				100,000,000				$ 100,000,000
Unmodified June 2019 Swap Agreements
Summary of Significant Accounting Policies
Notional amount				$ 200,000,000				$ 200,000,000
April 2020 Counter-agreements
Summary of Significant Accounting Policies
Notional amount							$ 300,000,000
Second Amended and Restated Term Loan B
Summary of Significant Accounting Policies
Repayments of Debt	$ 315,000,000
Second Amended and Restated Term Loan B | Interest Rate Swap
Summary of Significant Accounting Policies
Number of agreements | item									2	3
Notional amount									$ 400,000,000	$ 300,000,000
Minimum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				20 years
Maximum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				25 years
Rides and attractions | Minimum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				5 years
Rides and attractions | Maximum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				25 years
Land improvements | Minimum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				10 years
Land improvements | Maximum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				15 years
Buildings and improvements
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				30 years
Furniture and Equipment | Minimum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				5 years
Furniture and Equipment | Maximum
Summary of Significant Accounting Policies
Property, plant and equipment, useful life				10 years

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)item	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2020USD ($)	Jan. 01, 2019USD ($)
Revenue
Revenues	$ 108,602	$ 126,327	$ 19,143	$ 102,503	$ 261,000	$ 621,180	$ 477,210	$ 128,193	$ 356,575	$ 1,487,583	$ 1,463,707
Number of distinct obligations within international agreements | item	3								3
Long-term contracts
Revenue
Revenues									$ 51,820	198,507	212,584
Contract with customer, liability					$ 85,100					85,100		$ 85,100	$ 100,800
Contract with customer, liability, revenue recognized									51,200	161,000
Short-term contracts and other
Revenue
Revenues									304,755	1,289,076	1,251,123
Park admissions
Revenue
Revenues									202,646	815,782	810,064
Park admissions | Long-term contracts
Revenue
Revenues									28,627	106,233	115,612
Park admissions | Short-term contracts and other
Revenue
Revenues									174,019	709,549	694,452
Park food, merchandise and other
Revenue
Revenues									126,306	574,440	553,527
Park food, merchandise and other | Long-term contracts
Revenue
Revenues									2,431	20,381	25,383
Park food, merchandise and other | Short-term contracts and other
Revenue
Revenues									123,875	554,059	528,144
Sponsorship international agreements and accommodations
Revenue
Revenues									27,623	97,361	100,116
Sponsorship international agreements and accommodations | Long-term contracts
Revenue
Revenues									20,762	71,893	71,589
Sponsorship international agreements and accommodations | Short-term contracts and other
Revenue
Revenues									$ 6,861	$ 25,468	$ 28,527

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020	Jan. 01, 2019
Summary of Significant Accounting Policies
Accumulated deficit	$ (2,153,368)				$ (1,709,747)				$ (2,153,368)	$ (1,709,747)
Income tax (benefit) expense									(140,967)	91,942	$ 95,855
Revenues	108,602	$ 126,327	$ 19,143	$ 102,503	261,000	$ 621,180	$ 477,210	$ 128,193	356,575	1,487,583	1,463,707
Long-term contracts
Summary of Significant Accounting Policies
Revenues									51,820	198,507	$ 212,584
Contract with customer, liability					$ 85,100					85,100		$ 85,100	$ 100,800
Unearned contract with customer revenue recognized									51,200	$ 161,000
Performance obligation	$ 77,600								$ 77,600

Revenue - Performance Obligatio

Revenue - Performance Obligations (Details) - Long-term contracts $ in Millions	Dec. 31, 2020USD ($)
Revenue
Performance obligation	$ 77.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue
Performance obligation	$ 96.8
Expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue
Performance obligation	$ 19.2
Expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue
Performance obligation	$ 9.2
Expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue
Performance obligation	$ 1.3
Expected timing of satisfaction, period

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property and Equipment
Property and equipment, at cost	$ 2,408,690	$ 2,345,283
Accumulated depreciation	(1,157,403)	(1,061,287)
Total property and equipment, net	1,251,287	1,283,996
Land
Property and Equipment
Property and equipment, at cost	219,453	221,616
Land improvements
Property and Equipment
Property and equipment, at cost	274,089	264,417
Buildings and improvements
Property and Equipment
Property and equipment, at cost	324,943	318,960
Rides and attractions
Property and Equipment
Property and equipment, at cost	1,207,029	1,213,543
Equipment and other
Property and Equipment
Property and equipment, at cost	$ 383,176	$ 326,747

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets
Goodwill	$ 659,618	$ 659,618
Amortization	1,014	$ 2,405	$ 2,447
Finite life intangible assets written off	$ 24,000

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets
Indefinite-lived intangible assets	$ 344,075	$ 344,075
Goodwill and Intangible Assets
Accumulated Amortization	(238)	(23,224)
Net Carrying Value	123
Intangible assets, gross	344,436	368,436
Total intangible assets, net	$ 344,198	$ 345,212
Licensing Agreements
Goodwill and Intangible Assets
Weighted-Average Remaining Amortization Period (Years)	5 years 6 months	6 months
Gross Carrying Value	$ 361	$ 24,361
Accumulated Amortization	(238)	(23,224)
Net Carrying Value	$ 123	$ 1,137

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Amortization (Details) $ in Thousands	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets
2021	$ 22
2022	22
2023	22
2024	22
2025	22
2026 and thereafter	13
Net Carrying Value	$ 123

Noncontrolling Interests, Par_3

Noncontrolling Interests, Partnerships and Joint Ventures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in redeemable noncontrolling interests
Redeemable noncontrolling interests, beginning balance	$ 529,258	$ 525,271
Purchase of redeemable units	(4,976)	(217)	$ (353)
Fresh start accounting fair market value adjustment for purchased units	(924)	(45)
Change in redemption value of partnership units	(18)	(4,249)
Net income attributable to noncontrolling interests	41,288	40,753
Distributions to noncontrolling interests	(41,288)	(40,753)
Redeemable noncontrolling interests, ending balance	523,376	529,258	525,271
Six Flags over Texas
Changes in redeemable noncontrolling interests
Redeemable noncontrolling interests, beginning balance	246,744	243,756
Purchase of redeemable units	(3,440)	(217)
Fresh start accounting fair market value adjustment for purchased units	(720)	(45)
Change in redemption value of partnership units	(11)	(3,250)
Net income attributable to noncontrolling interests	20,634	20,452
Distributions to noncontrolling interests	(20,634)	(20,452)
Redeemable noncontrolling interests, ending balance	242,595	246,744	243,756
Six Flags over Georgia
Changes in redeemable noncontrolling interests
Redeemable noncontrolling interests, beginning balance	282,514	281,515
Purchase of redeemable units	(1,536)	0
Fresh start accounting fair market value adjustment for purchased units	(204)	0
Change in redemption value of partnership units	(7)	(999)
Net income attributable to noncontrolling interests	20,654	20,301
Distributions to noncontrolling interests	(20,654)	(20,301)
Redeemable noncontrolling interests, ending balance	$ 280,781	$ 282,514	$ 281,515

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Apr. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2020	Mar. 31, 2020	Aug. 31, 2019	Jun. 30, 2019
Derivative Financial Instruments
Repayment of borrowings		$ 526,510	$ 802,750	$ 274,000
Interest expense		155,411	$ 114,703	$ 108,034
Reclassification out of Accumulated Other Comprehensive Income
Derivative Financial Instruments
Interest expense	$ 14,900
Second Amended and Restated Term Loan B
Derivative Financial Instruments
Repayment of borrowings	$ 315,000
Interest Rate Swap
Derivative Financial Instruments
Notional amount								$ 300,000
Interest Rate Swap | Second Amended and Restated Term Loan B
Derivative Financial Instruments
Notional amount							$ 400,000	$ 300,000
Modified June 2019 Swap Agreement
Derivative Financial Instruments
Notional amount		100,000				$ 100,000
Unmodified June 2019 Swap Agreements
Derivative Financial Instruments
Notional amount		$ 200,000				$ 200,000
April 2020 Counter-agreements
Derivative Financial Instruments
Notional amount					$ 300,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Derivative Instruments Recorded at Fair Value (Details) - Interest Rate Swap - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivative Financial Instruments
Derivative Assets	$ 1,462	$ 1,925
Derivative Liabilities	(30,791)	(3,455)
Derivatives Designated as Cash Flow Hedges
Derivative Financial Instruments
Derivative Assets - Current		485
Derivative Assets - Noncurrent		1,440
Derivative Liabilities - Current	(5,251)	(788)
Derivative Liabilities - Noncurrent	(11,633)	$ (2,667)
Derivatives Not Designated as Hedging Instruments
Derivative Financial Instruments
Derivative Assets - Current	877
Derivative Assets - Noncurrent	585
Derivative Liabilities - Current	(4,875)
Derivative Liabilities - Noncurrent	$ (9,032)

Derivative Financial Instrume_5

Derivative Financial Instruments - Gains and Losses before Taxes on Derivatives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative Financial Instruments
Loss to be reclassified from AOCI to operations during the next twelve months	$ 5,300
Derivatives Designated as Cash Flow Hedges
Derivative Financial Instruments
Loss recognized in AOCI	(33,902)	$ (484)
Loss Reclassified from AOCI into Operations (Effective Portion)	(3,685)	1,046
Derivatives Designated as Cash Flow Hedges | Interest Rate Swap
Derivative Financial Instruments
Loss recognized in AOCI	(33,902)	(484)
Loss Reclassified from AOCI into Operations (Effective Portion)	(3,685)	$ 1,046
Derivatives Not Designated as Hedging Instruments
Derivative Financial Instruments
Loss recognized in Interest Expense	$ 600

Long-Term Indebtedness - Additi

Long-Term Indebtedness - Additional Information (Details)	Apr. 22, 2020USD ($)	Oct. 18, 2019USD ($)	Oct. 17, 2019	Apr. 17, 2019USD ($)	Apr. 13, 2017USD ($)	Jan. 31, 2017USD ($)	Jun. 16, 2016USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Apr. 30, 2020USD ($)	Apr. 08, 2020USD ($)	Apr. 07, 2020USD ($)	Aug. 31, 2019USD ($)item	Jun. 30, 2019USD ($)item	Apr. 16, 2019USD ($)
Summary of Long-term debt
Payments of debt issuance costs									$ 24,987,000	$ 9,911,000	$ 793,000
Loss on debt extinguishment, net									6,106,000	6,484,000	$ 0
Long-term debt									2,653,490,000
Proceeds from issuance of debt utilized for extinguishment of existing debt instruments							$ 150,000,000
Interest Rate Swap
Summary of Long-term debt
Notional amount																$ 300,000,000
Interest Rate Swap Second Agreements
Summary of Long-term debt
Notional amount															$ 400,000,000
LIBOR
Summary of Long-term debt
Basis spread on variable rate			2.00%
Amended And Restated Revolving Loan
Summary of Long-term debt
Maximum borrowing capacity									481,000,000
Letters of credit outstanding, amount									$ 21,000,000	20,800,000
Commitment fee percentage									0.30%
Amended And Restated Term Loan B
Summary of Long-term debt
Maximum borrowing capacity									$ 479,000,000
Loss on debt extinguishment, net	$ 5,100,000
Repayment of debt	315,000,000
2015 Revolving Loan
Summary of Long-term debt
Maximum borrowing capacity																	$ 250,000,000
Credit Facility 2015 - Term Loan B
Summary of Long-term debt
Maximum borrowing capacity																	$ 700,000,000
Amended And Restated Term Loan B As Amended June 2017
Summary of Long-term debt
Long-term debt									$ 479,000,000	$ 796,000,000
Interest rate, stated percentage									3.01%	3.48%
Second Amended and Restated Credit Facility
Summary of Long-term debt
Payments of debt issuance costs				$ 8,900,000
Second Amended and Restated Revolving Loan
Summary of Long-term debt
Maximum borrowing capacity				350,000,000									$ 481,000,000	$ 350,000,000
Long-term line of credit									$ 0	$ 0
Incremental borrowing capacity									131,000,000				$ 131,000,000
Second Amended and Restated Term Loan B
Summary of Long-term debt
Maximum borrowing capacity				800,000,000				$ 350,000,000				$ 481,000,000
Basis spread reduction		0.25%
Loss on debt extinguishment, net		$ 300,000		$ 6,200,000
Incremental borrowing capacity												131,000,000
Long-term debt									479,000,000	796,000,000
Repayment of debt	315,000,000
Annual interest cost savings from borrowing rate reduction		$ (2,000,000)
Second Amended and Restated Term Loan B | Interest Rate Swap
Summary of Long-term debt
Number of agreements | item															2	3
Notional amount															$ 400,000,000	$ 300,000,000
Second Amended and Restated Term Loan B | LIBOR
Summary of Long-term debt
Basis spread on variable rate		1.75%
Senior Unsecured 2024 Notes
Summary of Long-term debt
Payments of debt issuance costs							4,700,000
Loss on debt extinguishment, net								1,000,000
Long-term debt								949,500,000	949,490,000	1,000,000,000
Debt instrument, face amount							$ 300,000,000
Interest rate, stated percentage							4.875%
Periodic payment of interest					$ 24,400,000	$ 9,100,000		23,100,000
Pre-payment								$ 50,500,000
Senior Unsecured 2024 Notes Add-on
Summary of Long-term debt
Payments of debt issuance costs					3,900,000
Debt instrument, face amount					$ 700,000,000
Interest rate, stated percentage					4.875%
Senior Unsecured 2025 Notes
Summary of Long-term debt
Long-term debt									725,000,000
Debt instrument, face amount												$ 725,000,000
Interest rate, stated percentage												7.00%
Periodic payment of interest									25,400,000
Period payment of interest - first payment									35,100,000
Senior Unsecured 2025 Notes | Six Flags Theme Parks Inc.
Summary of Long-term debt
Debt instrument, face amount	$ 725,000,000
Interest rate, stated percentage	7.00%
Senior Unsecured 2027 Notes
Summary of Long-term debt
Payments of debt issuance costs					$ 2,600,000
Long-term debt									$ 500,000,000	$ 500,000,000
Debt instrument, face amount					$ 500,000,000
Interest rate, stated percentage					5.50%

Long-Term Indebtedness - Schedu

Long-Term Indebtedness - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Summary of Long-term debt
Long-term debt	$ 2,653,490
Net discount	(4,357)		$ (6,535)
Deferred financing costs	(26,492)		(14,581)
Total debt	2,622,641		2,274,884
Less current portion			(8,000)
Total long-term debt	2,622,641		2,266,884
Second Amended and Restated Term Loan B
Summary of Long-term debt
Long-term debt	479,000		796,000
Senior Unsecured 2024 Notes
Summary of Long-term debt
Long-term debt	949,490	$ 949,500	1,000,000
Senior Unsecured 2025 Notes
Summary of Long-term debt
Long-term debt	725,000
Senior Unsecured 2027 Notes
Summary of Long-term debt
Long-term debt	500,000		500,000
Estimate of Fair Value Measurement
Summary of Long-term debt
Total long-term debt	$ 2,693,300		$ 2,348,900

Long-Term Indebtedness - Sche_2

Long-Term Indebtedness - Schedule of Maturities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Long-Term Indebtedness
2024	$ 949,490
2025	725,000
2026 and thereafter	979,000
Long-term debt, gross	$ 2,653,490

Selling, General and Administ_3

Selling, General and Administrative Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Selling, General and Administrative Expenses
Selling, general and administrative expenses	$ 147,295	$ 199,194	$ 132,168
Allocated share-based compensation expense	19,530	13,274	(46,684)
Operating Segments
Selling, General and Administrative Expenses
Selling, general and administrative expenses	80,027	131,619	129,335
Corporate
Selling, General and Administrative Expenses
Selling, general and administrative expenses	67,268	67,575	2,833
Allocated share-based compensation expense	$ 19,500	$ 13,300	$ (46,700)

Stock Benefit Plans - Additiona

Stock Benefit Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2014	Feb. 08, 2012
Stock Benefit Plans
Allocated share-based compensation expense		$ 19,530	$ 13,274	$ (46,684)
Stock Options
Stock Benefit Plans
Percent based on historical data		75.00%
Percent based on forward-looking data		25.00%
Long Term Incentive Plan
Stock Benefit Plans
Number of additional shares authorized (in shares)	4,000,000
Shares available for future grant (in shares)		4,375,000
Long Term Incentive Plan | Stock Options
Stock Benefit Plans
Options to purchase common stock outstanding (in shares)		4,797,000	6,408,000
Award vesting period		4 years
Expiration period		10 years
Compensation cost not yet recognized		$ 5,600
Period for recognition		2 years 5 months 4 days
Unvested stock options outstanding (in shares)							10,000,000
Threshold for accumulated accrued dividend distribution to receive cash dividends (in shares)		1,000
Threshold for accumulated accrued dividend distribution to receive stock dividends (in shares)		1,000
Granted (in shares)		9,000	2,000,000	1,500,000
Long Term Incentive Plan | 2017 Performance Award
Stock Benefit Plans
Allocated share-based compensation expense		$ 19,100	$ 13,000	$ 15,500
Modified EBITDA for additional performance award						$ 600,000
Unrecognized share-based compensation		$ 0
Long Term Incentive Plan | 2020 Performance Award
Stock Benefit Plans
Modified EBITDA for additional performance award					$ 750,000
Potential grants based on performance criteria (in shares)		1,025,000
Long Term Incentive Plan | Restricted Stock And Restricted Stock Units
Stock Benefit Plans
Nonvested, number (in shares)		1,581,000
Long Term Incentive Plan | Deferred Stock Units
Stock Benefit Plans
Compensation cost not yet recognized		$ 0
Number of Shares to be Issued for each award (in shares)		1
Period after which shares are to be delivered		30 days
Granted (in shares)		7,000	4,000	3,000
Weighted average grant date fair value of stock awards granted (in dollars per share)		$ 31.43	$ 50.12	$ 57.04
Total grant date fair value of stock awards granted		$ 200	$ 200	$ 200
Long Term Incentive Plan | Dividend Equivalent Rights
Stock Benefit Plans
Allocated share-based compensation expense		300	5,000	5,900
Employee Stock Purchase Plan
Stock Benefit Plans
Allocated share-based compensation expense		$ 452	$ 237	$ 285
Percentage of the market value of common stock at beginning or end of the offering period for shares eligible to be purchased		90.00%
Number of shares of common stock that may be issued under the Plan (in shares)		2,000,000
Shares in ESOP (in shares)		1,579,000

Stock Benefit Plans - Weighted-

Stock Benefit Plans - Weighted-average Assumptions (Details) - Long Term Incentive Plan - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CEO
Stock Benefit Plans
Risk-free interest rate		1.59%	2.52%
Expected life (in years)		3 years 8 months 1 day	3 years 10 months 6 days
Expected volatility		28.62%	23.20%
Expected dividend yield		6.47%	4.67%
Employees
Stock Benefit Plans
Risk-free interest rate	1.60%	1.42%	2.67%
Expected life (in years)	3 years 8 months 1 day	3 years 8 months 1 day	3 years 8 months 4 days
Expected volatility	28.38%	26.96%	22.51%
Expected dividend yield	7.18%	6.12%	4.54%

Stock Benefit Plans - Stock Opt

Stock Benefit Plans - Stock Option Activity (Details) - Long Term Incentive Plan - Stock Options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding
Options outstanding at the beginning of the period (in shares)	6,408
Granted (in shares)	9	2,000	1,500
Exercised (in shares)	(127)
Canceled or exchanged (in shares)	(1,061)
Forfeited (in shares)	(432)
Expired (in shares)	0
Options outstanding at the end of the period (in shares)	4,797	6,408
Vested and expected to vest at the end of the period (in shares)	4,679
Options exercisable at end of the period (in shares)	2,993
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price
Outstanding, Weighted average exercise price at the beginning of the period (in dollars per share)	$ 52.42
Grants in period, Weighted average exercise price (in dollars per share)	44.73
Exercised, Weighted average exercise price (in dollars per share)	17.64
Canceled or exchanged, Weighted average exercise price (in dollars per share)	53.50
Forfeited, Weighted average exercise price (in dollars per share)	59.85
Expired, Weighted average exercise price (in dollars per share)	0
Outstanding, Weighted average exercise price at the end of the period (in dollars per share)	52.42	$ 52.42
Vested and expected to vest, Weighted average exercise price (in dollars per share)	52.23
Options exercisable at period end, Weighted average exercise price (in dollars per share)	$ 49.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term
Balance at the end of the period, Weighted average remaining contractual term	6 years 3 months 7 days
Vested and expected to vest at the end of the period, Weighted average remaining contractual term	6 years 2 months 19 days
Options exercisable at the end of the period. Weighted average remaining contractual term	5 years 29 days
Share Based Compensation Arrangement by Share Based Payment Award, Options, Intrinsic Value
Balance at the end of the period, Aggregate Intrinsic Value	$ 2,569
Vested and expected to vest at the end of the period, Aggregate Intrinsic Value	2,569
Options exercisable at the end of the period, Aggregate Intrinsic Value	$ 2,569

Stock Benefit Plans - Aspects o

Stock Benefit Plans - Aspects of Awards Exercised (Details) - Long Term Incentive Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options
Stock Benefit Plans
Weighted average grant date fair value of options granted	$ 4.85	$ 6.38	$ 8.01
Total intrinsic value of options exercised	$ 1,275	$ 7,130	$ 31,822
Total fair value of options that have vested	7,369	10,253	8,446
Total cash received from the exercise of stock options	2,235	$ 17,495	$ 41,658
Compensation cost not yet recognized	$ 5,600
Period for recognition	2 years 5 months 4 days
Stock, Restricted Stock and Restricted Stock Units
Stock Benefit Plans
Weighted average grant date fair value of stock awards granted (in dollars per share)	$ 18.86	$ 48.29	$ 63.80
Total grant date fair value of stock awards granted	$ 29,597	$ 3,007	$ 4,185
Total fair value of stock awards that have vested	2,011	$ 1,027	$ 3,888
Compensation cost not yet recognized	$ 17,600
Period for recognition	2 years 4 months 9 days

Stock Benefit Plans - Summary o

Stock Benefit Plans - Summary of Stock, Restricted Stock, and Restricted Stock Unit Activity (Details) - Long Term Incentive Plan - Stock, Restricted Stock and Restricted Stock Units - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Non-vested balance at the beginning of the period (in shares)	62
Granted (in shares)	1,569
Vested (in shares)	(50)
Forfeited (in shares)	(121)
Canceled (in shares)	0
Non-vested balance at the end of the period (in shares)	1,460	62
Weighted Average Grant Date Fair Value Per Share ($)
Non-vested balance at the beginning of the period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 48.29
Granted, Weighted Average Grant Date Fair Value (in dollars per share)	18.86	$ 48.29	$ 63.80
Vested, Weighted Average Grant Date Fair Value (in dollars per share)	40.19
Forfeited, Weighted Average Grant Date Fair Value (in dollars per share)	19.01
Canceled (in dollars per share)	0
Non-vested balance at the end of the period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 19.37	$ 48.29

Stock Benefit Plans - Stock-bas

Stock Benefit Plans - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Benefit Plans
Stock-based compensation	$ 19,530	$ 13,274	$ (46,684)
Long Term Incentive Plan | Options and other
Stock Benefit Plans
Stock-based compensation	19,078	13,037	15,543
Long Term Incentive Plan | Performance awards
Stock Benefit Plans
Stock-based compensation			(62,512)
Employee Stock Purchase Plan
Stock Benefit Plans
Stock-based compensation	$ 452	$ 237	$ 285

Income Taxes - Foreign and Dome

Income Taxes - Foreign and Domestic Components of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Domestic	$ (487,594)	$ 297,752	$ 383,875
Foreign	(35,464)	14,008	27,983
Income before income taxes	$ (523,059)	$ 311,760	$ 411,858

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Benefit) from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
U.S. federal	$ (3,530)	$ (2,960)	$ (58)
Foreign		5,812	11,752
State and local	(3,239)	10,704	11,268
Income tax expense	(6,769)	13,556	22,962
Deferred
U.S. federal	(99,976)	67,975	65,976
Foreign	(7,642)	1,169	626
State and local	(26,580)	9,242	6,291
Income tax expense	(134,199)	78,386	72,893
U.S. federal	(103,506)	65,015	65,918
Foreign	(7,642)	6,981	12,378
State and local	(29,819)	19,946	17,559
Income Tax Expense (Benefit), Total	$ (140,967)	$ 91,942	$ 95,855

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Computed expected federal income tax expense	$ (109,842)	$ 65,470	$ 86,490
Effect of noncontrolling interest income distribution	(8,671)	(8,558)	(8,401)
Change in valuation allowance	(2,482)	15,469	1,663
Effect of state and local income taxes, net of federal tax benefit	(14,356)	18,622	12,980
Deductible compensation in excess of book	773	(2,029)	(5,392)
Nondeductible compensation	951	635	1,167
Effect of foreign income taxes	(4,072)	2,084	4,544
Effect of foreign earnings earned and remitted in the same year		(302)	2,317
Effect of foreign tax credits	(528)	(407)	(996)
Other, net	(2,740)	958	1,483
Income Tax Expense (Benefit), Total	$ (140,967)	$ 91,942	$ 95,855

Income Taxes - Components of Ta

Income Taxes - Components of Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Deferred tax assets	$ 326,023	$ 191,349
Less: Valuation allowance	128,159	130,641
Net deferred tax assets	197,864	60,708
Net deferred tax liability	101,831	247,121
Deferred tax assets:
Federal net operating loss carryforwards	115,168	12,615
State net operating loss carryforwards	118,063	107,303
Deferred compensation	9,307	8,240
Foreign tax credits	21,367	20,469
Alternative minimum tax credits		3,296
Accrued insurance, pension liability and other	62,118	39,426
Total deferred tax assets	326,023	191,349
Deferred tax liabilities:
Property and equipment	220,927	226,872
Intangible assets and other	78,768	80,957
Deferred tax liabilities	$ 299,695	$ 307,829

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	May 01, 2010	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards
U.S. federal income tax rate (as a percent)		21.00%	21.00%	21.00%
Reduction in net operating loss as a result of emergence from Chapter 11	$ 804,800
Estimated annual limitation		$ 32,500
Foreign tax credits		21,367	$ 20,469
Valuation allowance		128,159	130,641
Foreign tax credits valuation allowance		18,000
Unrecognized tax benefit		25,400	$ 25,700
U.S. Federal
Operating Loss Carryforwards
Net operating loss carryforwards		600,000
State
Operating Loss Carryforwards
Net operating loss carryforwards		$ 6,300,000
Minimum
Operating Loss Carryforwards
Property, plant and equipment, useful life		20 years
Property, plant and equipment, useful life, tax		1 year
Maximum
Operating Loss Carryforwards
Property, plant and equipment, useful life		25 years

Preferred Stock, Common Stock_3

Preferred Stock, Common Stock and Other Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Thousands	Mar. 31, 2020item$ / shares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Feb. 19, 2021USD ($)$ / sharesshares	Mar. 30, 2017USD ($)
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Common stock, shares authorized (in shares)		280,000,000	280,000,000
Common stock, shares outstanding (in shares)		85,075,901	84,633,845
Value of shares repurchased | $		$ 54	$ 52	$ 110,990
Preferred stock, shares authorized		5,000,000
Preferred stock, shares issued		0
Preferred stock, shares authorized for future issuance		0
Par value | $ / shares		$ 1	$ 1
March 2017 Stock Repurchase Plan
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Amount authorized of shares to be repurchased under Stock Repurchase Program | $						$ 500,000
Total number of shares purchased (in shares)					4,607,000
Value of shares repurchased | $					$ 268,300
Shares acquired, average cost (in dollars per share) | $ / shares					$ 58.25
Permitted dollar value of repurchases remaining | $					$ 231,700
Long Term Incentive Plan
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Shares available for future grant (in shares)		4,375,000
Employee Stock Purchase Plan
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Shares in ESOP (in shares)		1,579,000
Preferred share purchase right
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Dividend, Preferred share purchase right | item	1
Exercisable exercise price of the Right | item	2
Share price | $ / shares	$ 75
Term of rights plan	1 year
Series B Junior Preferred Stock | Preferred share purchase right
Preferred Stock, Common Stock and Other Stockholders' Equity (Deficit)
Percentage of purchase of a preferred shares represented by rights	0.001
Par value | $ / shares	$ 1

Preferred Stock, Common Stock_4

Preferred Stock, Common Stock and Other Stockholders' Equity - Dividends (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Preferred Stock, Common Stock and Other Stockholders' Equity
Cash dividends per share of common stock paid (in dollars per share)	$ 0.25	$ 0.83	$ 0.82	$ 0.82	$ 0.82	$ 0.82	$ 0.78	$ 0.78	$ 0.78

Preferred Stock, Common Stock_5

Preferred Stock, Common Stock and Other Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive (Loss) Income
Beginning balance	$ (716,118)	$ (643,093)	$ (505,112)
Ending balance	(1,158,547)	(716,118)	(643,093)
Cumulative Translation Adjustment
Accumulated Other Comprehensive (Loss) Income
Beginning balance	(22,184)	(27,352)	(28,822)
Net current period change	5,228	5,168	1,470
Ending balance	(27,412)	(22,184)	(27,352)
Cash Flow Hedges
Accumulated Other Comprehensive (Loss) Income
Beginning balance	(1,530)
Net current period change	33,902	(484)
Amounts reclassified from AOCI	3,685	(1,046)
Amounts reclassified due to de-designation	14,928
Ending balance	(16,819)	(1,530)
Defined Benefit Plans
Accumulated Other Comprehensive (Loss) Income
Beginning balance	(49,282)	(41,071)	(41,959)
Net current period change	9,345	(9,006)	167
Amounts reclassified from AOCI	985	795	721
Ending balance	(57,642)	(49,282)	(41,071)
Income Taxes
Accumulated Other Comprehensive (Loss) Income
Beginning balance	(1,714)	(3,075)	6,900
Net current period change	(11,968)	1,283	(351)
Amounts reclassified from AOCI	(1,165)	78	(185)
Amounts reclassified due to de-designation	(3,720)
Ending balance	5,369	(1,714)	(3,075)
Income Taxes | Accounting Standards Update, 2018-02 | Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive (Loss) Income
Beginning balance			(9,439)
Accumulated other comprehensive loss
Accumulated Other Comprehensive (Loss) Income
Beginning balance	(74,710)	(71,498)	(63,881)
Net current period change	36,507	(3,039)	1,286
Amounts reclassified from AOCI	3,505	(173)	536
Amounts reclassified due to de-designation	11,208
Ending balance	$ (96,504)	$ (74,710)	(71,498)
Accumulated other comprehensive loss | Accounting Standards Update, 2018-02 | Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive (Loss) Income
Beginning balance			$ (9,439)

Preferred Stock, Common Stock_6

Preferred Stock, Common Stock and Other Stockholders' Equity - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	Apr. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassifications out of accumulated other comprehensive income (loss):
Interest expense		$ (155,411)	$ (114,703)	$ (108,034)
Income tax expense		140,967	(91,942)	(95,855)
Net income		(382,092)	219,818	316,003
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income (loss):
Interest expense	$ (14,900)
Net income		3,505	(173)	536
Reclassification out of Accumulated Other Comprehensive Income | Amortization of loss on interest rate hedge
Reclassifications out of accumulated other comprehensive income (loss):
Interest expense		3,685	(1,046)
Income tax expense		(917)	276
Net income		2,768	(770)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of deferred actuarial loss and prior service cost
Reclassifications out of accumulated other comprehensive income (loss):
Operating expenses		985	795	721
Income tax expense		(248)	(198)	(185)
Net income		$ 737	$ 597	$ 536

Pension Benefits - Additional I

Pension Benefits - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018
Pension Benefits
Normal retirement age (in years)	65 years
Early retirement age, low end of range (in years)	55 years
Early retirement age, high end of range (in years)	64 years
Attainment of credited service (in years)	10 years
Threshold age for reduction in early retirement benefit (in years)	62 years
Number of highest consecutive period of average compensation, used in plan benefit calculation (in years)	5 years
Period of average compensation, used in plan benefit calculation (in years)	10 years
Funded status (deficit)	$ (18.4)	$ (16)
AOCI, defined benefit plan, after tax	64.6	56.1
AOCI, defined benefit plan, tax	(7)	$ (6.8)
Estimated amount to be amortized from AOCI	$ 1.4
Number of a high grade bonds considered when selecting discount rate | item	500
Expected return on plan assets	6.50%	7.25%	7.25%
Domestic equity securities
Pension Benefits
Target allocation, percent	4.00%
Fixed income securities
Pension Benefits
Target allocation, percent	63.00%
International Equity
Pension Benefits
Target allocation, percent	19.00%
Alternatives
Pension Benefits
Target allocation, percent	14.00%

Pension Benefits - Benefit Plan

Pension Benefits - Benefit Plan Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation:
Beginning balance	$ 221,458	$ 201,752	$ 218,746
Interest cost	6,431	7,993	7,386
Actuarial loss (gain)	18,243	25,632	(16,324)
Benefits paid	(9,006)	(13,919)	(8,056)
Benefit obligation at end of period	237,126	221,458	201,752
Change in fair value of plan assets:
Beginning balance	205,463	184,758	190,534
Actual return on assets	21,987	29,815	(2,497)
Employer contributions	1,500	6,000	6,000
Administrative fees	(9,006)	(13,918)	(1,223)
Benefits paid	(1,171)	(1,192)	(8,056)
Fair value of plan assets at end of period	$ 218,773	$ 205,463	$ 184,758

Pension Benefits - Assumptions

Pension Benefits - Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Discount rate to determine benefit obligations	2.20%	3.00%
Discount rate	3.00%	4.05%	3.45%
Expected return on plan assets	6.50%	7.25%	7.25%
Corridor	10.00%	10.00%	10.00%
Average future life expectancy (in years)	25 years 8 months 12 days	26 years 10 months 13 days	27 years 9 months 7 days

Pension Benefits - Net Periodic

Pension Benefits - Net Periodic Benefit and Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net periodic benefit cost:
Service cost	$ 1,200	$ 1,300	$ 1,300
Interest cost	6,431	7,993	7,386
Expected return on plan assets	(13,119)	(13,296)	(13,737)
Amortization of net actuarial loss	985	795	721
Total net periodic benefit	(4,503)	(3,208)	(4,330)
Other comprehensive income:
Current year actuarial gain	(9,345)	(9,006)	167
Recognized net actuarial loss	985	795	721
Total other comprehensive gain	$ (8,360)	$ (8,211)	$ 888

Pension Benefits - Plan Assets

Pension Benefits - Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Fair Value of Plan Assets	$ 218,773	$ 205,463	$ 184,758	$ 190,534
Minimum
Pension Benefits
Redemption notice	65 days
Maximum
Pension Benefits
Redemption notice	90 days
Large-Cap Disciplined Equity
Pension Benefits
Fair Value of Plan Assets	$ 8,065	6,844
International Equity
Pension Benefits
Fair Value of Plan Assets	42,178	35,962
Long Duration Fixed Income
Pension Benefits
Fair Value of Plan Assets	138,399	133,592
Other Investments
Pension Benefits
Fair Value of Plan Assets	30,131	29,065
Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension Benefits
Fair Value of Plan Assets	188,642	176,398
Quoted Prices in Active Markets for Identical Assets (Level 1) | Large-Cap Disciplined Equity
Pension Benefits
Fair Value of Plan Assets	8,065	6,844
Quoted Prices in Active Markets for Identical Assets (Level 1) | International Equity
Pension Benefits
Fair Value of Plan Assets	42,178	35,962
Quoted Prices in Active Markets for Identical Assets (Level 1) | Long Duration Fixed Income
Pension Benefits
Fair Value of Plan Assets	138,399	133,592
Quoted Prices in Active Markets for Identical Assets (Level 1) | High Yield
Pension Benefits
Fair Value of Plan Assets		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Emerging Markets Debt
Pension Benefits
Fair Value of Plan Assets		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Investments
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Observable Inputs (Level 2)
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Observable Inputs (Level 2) | Large-Cap Disciplined Equity
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Observable Inputs (Level 2) | International Equity
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Observable Inputs (Level 2) | Long Duration Fixed Income
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Observable Inputs (Level 2) | High Yield
Pension Benefits
Fair Value of Plan Assets		0
Significant Observable Inputs (Level 2) | Emerging Markets Debt
Pension Benefits
Fair Value of Plan Assets		0
Significant Observable Inputs (Level 2) | Other Investments
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3)
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Large-Cap Disciplined Equity
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | International Equity
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Long Duration Fixed Income
Pension Benefits
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | High Yield
Pension Benefits
Fair Value of Plan Assets		0
Significant Unobservable Inputs (Level 3) | Emerging Markets Debt
Pension Benefits
Fair Value of Plan Assets		0
Significant Unobservable Inputs (Level 3) | Other Investments
Pension Benefits
Fair Value of Plan Assets	$ 0	$ 0

Pension Benefits - Expected Cas

Pension Benefits - Expected Cash Flows (Details) $ in Thousands	Dec. 31, 2020USD ($)
Expected benefit payments:
2021	$ 10,578
2022	11,072
2023	11,407
2024	11,709
2026	11,958
2026 through 2030	60,744
Total expected benefit payments	$ 117,468

(Loss) Earnings Per Common Sh_3

(Loss) Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
(Loss) Earnings Per Common Share
Antidilutive stock options excluded from computation of diluted shares outstanding (in shares)									6,300	3,500	700
Calculation of earnings per common share
Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders	$ (85,768)	$ (116,172)	$ (136,894)	$ (84,546)	$ (11,155)	$ 179,833	$ 79,519	$ (69,132)	$ (423,380)	$ 179,065	$ 275,996
Weighted-average common shares outstanding:
Weighted-average common shares outstanding-basic (in shares)									84,800	84,348	84,100
Effect of dilutive stock options and restricted stock units (in shares)										620	1,345
Weighted-average common shares outstanding-diluted (in shares)									84,800	84,968	85,445
(Loss) earnings per share - basic (in dollars per share)	$ (1)	$ (1.37)	$ (1.62)	$ (1)	$ (0.13)	$ 2.13	$ 0.94	$ (0.82)	$ (4.99)	$ 2.12	$ 3.28
(Loss) earnings per share - diluted (in dollars per share)	$ (1)	$ (1.37)	$ (1.62)	$ (1)	$ (0.13)	$ 2.11	$ 0.94	$ (0.82)	$ (4.99)	$ 2.11	$ 3.23

Commitments and Contingencies (

Commitments and Contingencies (Details)

Apr. 08, 2020claim

Jan. 07, 2016USD ($)

Apr. 01, 1998USD ($)

May 31, 2020USD ($)shares

Apr. 30, 2020lawsuit

Mar. 31, 2020claim

Feb. 29, 2020claim

May 31, 2019USD ($)shares

Dec. 31, 2021USD ($)

Dec. 31, 2020USD ($)multiple

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017lawsuit

Apr. 07, 2017item

Details of commitments and contingencies

Acquisition of capital stock of the former Six Flags Entertainment Corporation, paid in cash

$ 976,000,000

Redemption value of noncontrolling interests

$ 523,400,000

Additions to property and equipment

100,878,000

$ 143,913,000

$ 135,624,000

Total loans receivable from the partnerships that own partnership parks

288,300,000

$ 239,300,000

Pending Litigation

Details of commitments and contingencies

Number of claims filed | claim

3

Privacy Class Action Lawsuits

Details of commitments and contingencies

Number of questions certified for consideration by appellate court | item

2

Privacy Class Action Lawsuits | Pending Litigation

Details of commitments and contingencies

Number of claims filed | lawsuit

4

Privacy Class Action Lawsuits | Pending Litigation | Minimum

Details of commitments and contingencies

Range of possible loss per aggrieved party

100

Privacy Class Action Lawsuits | Pending Litigation | Maximum

Details of commitments and contingencies

Range of possible loss per aggrieved party

1,000

Securities Class Action Lawsuits | Pending Litigation

Details of commitments and contingencies

Number of claims filed | claim

2

Stockholder Derivative Lawsuits | Pending Litigation

Details of commitments and contingencies

Number of claims filed | lawsuit

2

Number of claims consolidated | claim

3

BIPA | Privacy Class Action Lawsuits | Minimum

Details of commitments and contingencies

Range of possible loss per aggrieved party

$ 1,000

BIPA | Privacy Class Action Lawsuits | Maximum

Details of commitments and contingencies

Range of possible loss per aggrieved party

$ 5,000

Multi-layered general liability policies

Details of commitments and contingencies

Excess liability coverage per occurrence

100,000,000

Self-insured retention per occurrence

2,000,000

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

750,000

Information security and privacy liability insurance policy

Details of commitments and contingencies

Self-insured retention per occurrence

250,000

Insurance value maintained

10,000,000

Amended And Restated Term Loan B As Amended June 2017

Details of commitments and contingencies

Additional contingent borrowing capacity

$ 350,000,000

Six Flags over Georgia

Details of commitments and contingencies

Limited partner interests owned (as a percent)

31.40%

Remaining redeemable units (as a percent)

68.60%

Six Flags over Texas

Details of commitments and contingencies

Units purchased in partnership parks (in units) | shares

1.5675

Purchase price of partnership units

$ 3,400,000

Limited partner interests owned (as a percent)

53.90%

Remaining redeemable units (as a percent)

46.10%

Six Flags over Texas and Georgia

Details of commitments and contingencies

Share of Partnership Parks' annual distributions paid to Six Flags Entertainment Corporation

$ 33,300,000

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

$ 9,100,000

Cash generated from operating activities by partnerships, after deduction of capital expenditures and excluding the impact of short-term intercompany advances

$ 8,400,000

Six Flags over Georgia

Details of commitments and contingencies

Units purchased in partnership parks (in units) | shares

0.375

Purchase price of partnership units

$ 1,500,000

Specified multiple for purchase price valuation (in multipliers) | multiple

8

Specified price for purchase of partnership parks

$ 409,700,000

Six Flags over Texas

Details of commitments and contingencies

Units purchased in partnership parks (in units) | shares

0.1

Purchase price of partnership units

$ 200,000

Specified multiple for purchase price valuation (in multipliers) | multiple

8.5

Specified price for purchase of partnership parks

$ 527,400,000

Forecast | Six Flags over Texas and Georgia

Details of commitments and contingencies

Annual distributions by general partners to limited partners in partnership parks

$ 75,200,000

Additions to property and equipment

$ 10,200,000

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Leases
Option to terminate, term	1 year
Operating leases, rent expense, net		$ 29.3
Minimum
Leases
Term of contract	1 year
Maximum
Leases
Term of contract	45 years
Renewal term	20 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases
Amortization of ROU Assets	$ 248
Interest on Lease Liabilities	31
Operating lease cost	24,166	$ 24,890
Short-term lease cost	5,804	6,925
Variable lease cost	4,816	5,979
Total lease cost	35,065	37,794
Operating cash flows from operating leases	18,870	24,140
Financing cash flows from finance leases	490
Operating cash flows from finance leases	31
ROU assets obtained in exchange for lease liabilities	7,774	$ 4,808
ROU assets obtained in exchange for finance lease liabilities	$ 2,428
Weighted-average remaining lease term (in years)	18 years 9 months 29 days
Weighted-average discount rate	6.95%
Weighted-average remaining finance lease term (in years)	3 years 7 months 2 days
Weighted-average discount rate	3.81%

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Leases
Right of Use Assets, net	$ 196,711	$ 201,128	$ 207,400
Short-term lease liabilities	13,727	10,709
Long-term lease liabilities	185,823	188,149
Operating Lease, Liability, Total	$ 199,550	$ 198,858	$ 204,300
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OpertaingLeasLiabilityCurrent us-gaap:OpertaingLeasLiabilityNoncurrent	us-gaap:OpertaingLeasLiabilityCurrent us-gaap:OpertaingLeasLiabilityNoncurrent	us-gaap:OpertaingLeasLiabilityCurrent us-gaap:OpertaingLeasLiabilityNoncurrent
Property and equipment, at cost	$ 2,408,690	$ 2,345,283
Accumulated depreciation	(1,157,403)	(1,061,287)
Total property and equipment, net	1,251,287	$ 1,283,996
Short-term lease liabilities	327
Long-term lease liabilities	1,609
Total finance lease obligations	1,936
Finance Leases
Leases
Property and equipment, at cost	2,428
Accumulated depreciation	(248)
Total property and equipment, net	$ 2,180

Leases - Future Minimum Lease O

Leases - Future Minimum Lease Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Leases
2021	$ 26,859
2022	22,326
2023	22,225
2024	20,473
2025	18,388
Thereafter	261,746
Total	372,017
Less: present value discount	(172,467)
Lease liability	199,550	$ 198,858	$ 204,300
Finance Leases
2021	397
2022	651
2023	651
2024	384
Total	2,083
Less : present value discount	(147)
Lease Liability	$ 1,936

Business Segments - Schedule of

Business Segments - Schedule of Segment Financial Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Reconciliation of net loss to Park EBITDA
Number of reportable segments | segment	1
Net (loss) income	$ (382,092)	$ 219,818	$ 316,003
Interest expense, net	154,723	113,302	107,243
Income tax (benefit) expense	(140,967)	91,942	95,855
Depreciation and amortization	120,173	118,230	115,693
Stock-based compensation	19,530	13,274	(46,684)
Loss on disposal of assets	7,689	2,162	1,879
Loss on debt extinguishment, net	6,106	6,484	0
Other expense (income), net	24,993	2,542	3,508
Operating Segments
Reconciliation of net loss to Park EBITDA
Park EBITDA	(142,113)	622,055	642,176
Corporate
Reconciliation of net loss to Park EBITDA
Corporate expenses	47,732	54,301	48,679
Stock-based compensation	$ 19,500	$ 13,300	$ (46,700)

Business Segments - Information

Business Segments - Information by Geographic Region (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)item	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business segment information by geographical areas
Number of parks owned or operated | item	26								26
Long-lived assets	$ 2,451,814				$ 2,489,954				$ 2,451,814	$ 2,489,954	$ 2,262,329
Revenues	108,602	$ 126,327	$ 19,143	$ 102,503	261,000	$ 621,180	$ 477,210	$ 128,193	356,575	1,487,583	1,463,707
Income (loss) before income taxes	$ (112,782)	$ (131,771)	$ (171,911)	$ (106,595)	10,143	$ 261,835	$ 133,571	$ (93,789)	$ (523,059)	311,760	411,858
Mexico
Business segment information by geographical areas
Number of parks owned or operated | item	2								2
Canada
Business segment information by geographical areas
Number of parks owned or operated | item	1								1
Domestic
Business segment information by geographical areas
Long-lived assets	$ 2,317,009				2,347,578				$ 2,317,009	2,347,578	2,160,970
Revenues									334,713	1,370,367	1,335,787
Income (loss) before income taxes									(487,594)	297,752	383,875
Foreign
Business segment information by geographical areas
Long-lived assets	$ 134,805				$ 142,376				134,805	142,376	101,359
Revenues									21,862	117,216	127,920
Income (loss) before income taxes									$ (35,464)	$ 14,008	$ 27,983

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information (Unaudited)
Revenues	$ 108,602	$ 126,327	$ 19,143	$ 102,503	$ 261,000	$ 621,180	$ 477,210	$ 128,193	$ 356,575	$ 1,487,583	$ 1,463,707
Income (loss) before income taxes	(112,782)	(131,771)	(171,911)	(106,595)	10,143	261,835	133,571	(93,789)	(523,059)	311,760	411,858
Net (loss) income attributable to Six Flags Entertainment Corporation common stockholders	$ (85,768)	$ (116,172)	$ (136,894)	$ (84,546)	$ (11,155)	$ 179,833	$ 79,519	$ (69,132)	$ (423,380)	$ 179,065	$ 275,996
Net (loss) income per weighted average common share outstanding:
(Loss) earnings per share - basic (in dollars per share)	$ (1)	$ (1.37)	$ (1.62)	$ (1)	$ (0.13)	$ 2.13	$ 0.94	$ (0.82)	$ (4.99)	$ 2.12	$ 3.28
(Loss) earnings per share - diluted (in dollars per share)	$ (1)	$ (1.37)	$ (1.62)	$ (1)	$ (0.13)	$ 2.11	$ 0.94	$ (0.82)	$ (4.99)	$ 2.11	$ 3.23