Description of the Business and Significant Accounting Policies (Policies)	6 Months Ended
Jun. 29, 2025
Accounting Policies [Abstract]
Accounting Change	Accounting Change Former Cedar Fair recognized depreciation expense on a straight-line basis for each annual period but followed an accounting convention in interim periods to record depreciation expense over each park's operating season. Beginning on July 1, 2024, the Combined Company changed its interim basis of recording depreciation from park operating days to straight-line. This method was deemed to be preferable to improve internal comparability, achieve better industry comparability and provide a better representation of the impact on the value of fixed assets over time.
Reclassifications	Reclassifications As a result of the Mergers (described in Note 2), the Combined Company made certain reclassification adjustments to prior period amounts where it adopted the Former Six Flags classification as opposed to the Former Cedar Fair classification. These reclassifications had no net impact on net revenues, operating income (loss), net income (loss), cash flows, or total assets, liabilities and equity.
Contingencies	Contingencies The Combined Company is a party to a number of lawsuits in the normal course of business. In the opinion of management, none of these matters, beyond what has been disclosed in this Quarterly Report on Form 10-Q, are expected to have a material effect in the aggregate on the unaudited condensed consolidated financial statements.
Recently Adopted Accounting Pronouncements and New Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). ASU 2023-09 requires additional income tax disclosures, including amendments to the rate reconciliation and income taxes paid disclosure. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied on a prospective basis, but retrospective application is permitted. The amendment was adopted by the Combined Company in the first quarter of 2025, and the related consolidated financial statement disclosures will be included within the annual financial statements as required. New Accounting Pronouncements In November 2024, the FASB issued Accounting Standards Update No. 2024-03, Income Statement - Reporting Comprehensive Income (Subtopic 220-40): Expense Disaggregation Disclosures ("ASU 2024-03"). ASU 2024-03 requires additional information about specific expense categories in the notes to the financial statements. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026. Early adoption is permitted. The amendments should be applied either (1) prospectively to financial statements issued after the effective date or (2) retrospectively to all prior periods presented in the financial statements. Management is in the process of evaluating the effect this standard will have on the consolidated financial statement disclosures.
Earnings per Share	For purposes of calculating the basic and diluted earnings per share of common stock and limited partner unit, as applicable, net income (loss) attributable to Six Flags Entertainment Corporation for the three and six months ended June 29, 2025 and for the three and six months ended June 30, 2024 have not been adjusted from the reported amounts.

Description of the Business and Significant Accounting Policies (Policies)

6 Months Ended

Jun. 29, 2025

Former Cedar Fair recognized depreciation expense on a straight-line basis for each annual period but followed an accounting convention in interim periods to record depreciation expense over each park's operating season. Beginning on July 1, 2024, the Combined Company changed its interim basis of recording depreciation from park operating days to straight-line. This method was deemed to be preferable to improve internal comparability, achieve better industry comparability and provide a better representation of the impact on the value of fixed assets over time.

Reclassifications

As a result of the Mergers (described in Note 2), the Combined Company made certain reclassification adjustments to prior period amounts where it adopted the Former Six Flags classification as opposed to the Former Cedar Fair classification. These reclassifications had no net impact on net revenues, operating income (loss), net income (loss), cash flows, or total assets, liabilities and equity.

Contingencies

The Combined Company is a party to a number of lawsuits in the normal course of business. In the opinion of management, none of these matters, beyond what has been disclosed in this Quarterly Report on Form 10-Q, are expected to have a material effect in the aggregate on the unaudited condensed consolidated financial statements.

Recently Adopted Accounting Pronouncements and New Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). ASU 2023-09 requires additional income tax disclosures, including amendments to the rate reconciliation and income taxes paid disclosure. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied on a prospective basis, but retrospective application is permitted. The amendment was adopted by the Combined Company in the first quarter of 2025, and the related consolidated financial statement disclosures will be included within the annual financial statements as required.

New Accounting Pronouncements

In November 2024, the FASB issued Accounting Standards Update No. 2024-03, Income Statement - Reporting Comprehensive Income (Subtopic 220-40): Expense Disaggregation Disclosures ("ASU 2024-03"). ASU 2024-03 requires additional information about specific expense categories in the notes to the financial statements. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026. Early adoption is permitted. The amendments should be applied either (1) prospectively to financial statements issued after the effective date or (2) retrospectively to all prior periods presented in the financial statements. Management is in the process of evaluating the effect this standard will have on the consolidated financial statement disclosures.

Earnings per Share

For purposes of calculating the basic and diluted earnings per share of common stock and limited partner unit, as applicable, net income (loss) attributable to Six Flags Entertainment Corporation for the three and six months ended June 29, 2025 and for the three and six months ended June 30, 2024 have not been adjusted from the reported amounts.