Long-Term Debt - Additional Information (Detail)				12 Months Ended
	Aug. 05, 2020 USD ($)	Jul. 29, 2020 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) Swap	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 10, 2020 USD ($)	Oct. 31, 2018 USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 2,219,878,000	$ 1,557,883,000
Outstanding letters of credit				21,200,000
Discount initially recorded				21,900,000
Payment to lenders				$ 13,800,000
Loss on early extinguishment of debt and write-off of discounts and debt issuance costs						$ 8,150,000
Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Number of interest rate swaps held | Swap				5
Notional amount of interest rate swap				$ 1,000,000,000.0
Maturity of interest rate swap				May 14, 2020
Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Percentage of interest in subsidiary				100.00%
Line of credit facility collateral description				The Senior Secured Credit Facilities are collateralized by first priority or equivalent security interests, subject to certain exceptions, in (i) all the capital stock of, or other equity interests in, substantially all of SEA’s direct or indirect material domestic subsidiaries and 65% of the capital stock of, or other equity interests in, any “first tier” foreign subsidiaries and (ii) certain tangible and intangible assets of SEA and the Company.
Percentage of capital stock				65.00%
Cash paid for interest				$ 73,700,000	80,500,000	82,500,000
First-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Senior secured debt			$ 227,500,000
Long-term debt, maturity date			May 01, 2025
Percentage of interest in subsidiary			100.00%
Debt instrument interest rate percentage			8.75%
Date of first required payment			Nov. 02, 2020
Redemption description			On or after May 1, 2022, SEA may redeem the Senior Notes at its option, in whole at any time or in part from time to time, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, if redeemed during the 12-month period commencing on May 1 of the years as follows: (i) in 2022 at 104.375%; (ii) in 2023 at 102.188%; and (iii) in 2024 and thereafter at 100%. SEA may also redeem in the aggregate (at a redemption price expressed as a percentage of principal amount thereof): (i) 100% of the Senior Notes after certain events constituting a change of control at a redemption price of 101%, plus accrued and unpaid interest, if any, to, but excluding, the redemption date and (ii) up to 40% of the original aggregate principal amount of the Senior Notes with amounts equal to the net cash proceeds of certain equity offerings at a redemption price  of 108.375%, plus accrued and unpaid interest, if any, to, but excluding, the redemption date.
First-Priority Senior Secured Notes [Member] | In year 2022 [Member]
Debt Instrument [Line Items]
Redemption percentage			104.375%
First-Priority Senior Secured Notes [Member] | In year 2023 [Member]
Debt Instrument [Line Items]
Redemption percentage			102.188%
First-Priority Senior Secured Notes [Member] | In year 2024 and thereafter [Member]
Debt Instrument [Line Items]
Redemption percentage			100.00%
Second-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Senior secured debt	$ 500,000,000.0
Long-term debt, maturity date	Aug. 01, 2025
Debt instrument interest rate percentage	9.50%
Date of first required payment	Feb. 01, 2021
Redemption description	On or after February 1, 2022, SEA may redeem the Second-Priority Senior Notes at its option, in whole at any time or in part from time to time, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, if redeemed during the 12-month period commencing on February 1 of the years as follows: (i) in 2022 at 104.75%; (ii) in 2023 at 102.375%; and (iii) in 2024 and thereafter at 100%. SEA may also redeem in the aggregate (at a redemption price expressed as a percentage of principal amount thereof): (i) 100% of the Second-Priority Senior Notes after certain events constituting a change of control at a redemption price of 101%, plus accrued and unpaid interest, if any, to, but excluding, the redemption date and (ii) up to 40% of the original aggregate principal amount of the Second-Priority Senior Notes with amounts equal to the net cash proceeds of certain equity offerings at a redemption price  of 109.50%, plus accrued and unpaid interest, if any, to, but excluding, the redemption date.
Redemption percentage	101.00%
Percentage of Notes Redeemable after change of control	100.00%
Second-Priority Senior Secured Notes [Member] | In year 2022 [Member]
Debt Instrument [Line Items]
Redemption description	At any time prior to February 1, 2022, SEA may, (i) during the twelve month period commencing on the issue date and (ii) during the period subsequent to such twelve month period and prior to February 1, 2022, redeem in each period up to 10.0% of the initial aggregate principal amount of the Second-Priority Senior Notes at a redemption price equal to 103% of the aggregate principal amount of the Second-Priority Senior Notes to be redeemed plus accrued and unpaid interest, if any, to but excluding the redemption date; provided, that if SEA does not redeem 10.0% of the initial aggregate principal amount of Second-Priority Senior Notes during the twelve month period commencing on the issue date, SEA may, in the subsequent period prior to February 1, 2022, redeem the Second-Priority Senior Notes in an amount that does not exceed 10.0% of the initial aggregate principal amount plus the difference between (x) 10.0% of the initial aggregate principal amount and (y) the aggregate principal amount of Second-Priority Senior Notes that were redeemed in such twelve month period
Redemption percentage	104.75%
Initial aggregate principal amount, Allowable redeemable percentage	10.00%
Redeemable percentage	103.00%
Second-Priority Senior Secured Notes [Member] | In year 2023 [Member]
Debt Instrument [Line Items]
Redemption percentage	102.375%
Second-Priority Senior Secured Notes [Member] | In year 2024 and thereafter [Member]
Debt Instrument [Line Items]
Redemption percentage	100.00%
Second-Priority Senior Secured Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Redemption percentage	109.50%
Percentage Of Notes Redeemable	40.00%
Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured debt			$ 227,500,000
Long-term debt				$ 227,500,000
Debt instrument interest rate percentage			8.75%	8.75%
SEA [Member]
Debt Instrument [Line Items]
Loss on early extinguishment of debt and write-off of discounts and debt issuance costs						8,200,000
Term B-5 Loans [Member]
Debt Instrument [Line Items]
Long-term debt				$ 1,492,378,000	$ 1,507,883,000
Long-term debt, maturity date				Mar. 31, 2024
Percent of original principal amount on effective date used to calculate aggregate annual amounts which will amortize in equal quarterly installments								1.015%
Interest rate, description				Borrowings of the Term B-5 Loans under the Amended Credit Agreement bear interest at a fluctuating rate per annum equal to, at SEA’s option, (i) a base rate equal to the higher of (a) the federal funds rate plus 1/2 of 1% and (b) the rate of interest in effect for such day as publicly announced from time to time by JPMorgan Chase Bank, N.A. as its “prime rate” (provided that in no event shall such base rate with respect to the Term B-5 Loans be less than 1.75% per annum), in each case, plus an applicable margin of 2.00% or (ii) a LIBOR rate based on the British Bankers Association LIBOR Rate (or any successor thereto) for the applicable interest period (provided that in no event shall such LIBOR rate with respect to the Term B-5 Loans be less than 0.75% per annum) plus an applicable margin of 3.00%.
Debt instrument interest rate effective percentage				3.75%	4.80%
Discount initially recorded						700,000
Term B-5 Loans [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				0.50%
Term B-5 Loans [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				2.00%
Term B-5 Loans [Member] | Prime Rate [Member] | Minimum
Debt Instrument [Line Items]
Debt instrument interest rate effective percentage				1.75%
Term B-5 Loans [Member] | LIBOR Rate Loan [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				3.00%
Term B-5 Loans [Member] | LIBOR Rate Loan [Member] | Minimum
Debt Instrument [Line Items]
Debt instrument interest rate effective percentage				0.75%
Term B-5 Loans [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Senior secured debt								$ 543,900,000
Mandatory prepayments				$ 0	$ 0	$ 0
Redemption Price One [Member] | First-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Redemption percentage			101.00%
Redemption Price Two [Member] | First-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Redemption percentage			108.375%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Senior secured revolving				$ 332,500,000			$ 210,000,000.0
Long-term debt					$ 50,000,000
Long-term debt, maturity date				Oct. 31, 2023
Debt instrument, maturity date description				The Revolving Credit Facility will mature on October 31, 2023.
Interest rate, description				Borrowings of the Revolving Credit Facility under the Amended Credit Agreement bear interest at a fluctuating rate per annum equal to, at SEA’s option, (i) a base rate equal to the higher of (a) the federal funds rate plus 1⁄2 of 1% and (b) the rate of interest in effect for such day as publicly announced from time to time by JPMorgan Chase Bank, N.A. as its “prime rate”, in each case, plus an applicable margin equal to 1.75%; or (ii) a LIBOR rate based on the British Bankers Association LIBOR Rate (or any successor thereto) for the applicable interest period (provided that in no event shall such LIBOR rate with respect to the Revolving Credit Facility be less than 0.0% per annum) plus an applicable margin equal to 2.75%.  The applicable margin for borrowings under the Revolving Credit Facility are subject to one 25 basis point step-down upon achievement by SEA of certain corporate credit ratings, which the Company did not achieve as of December 31, 2020.
Debt instrument interest rate effective percentage					4.35%
Basis point step-down in applicable margin, description				The applicable margin for borrowings under the Revolving Credit Facility are subject to one 25 basis point step-down upon achievement by SEA of certain corporate credit ratings, which the Company did not achieve as of December 31, 2020.
Basis point step down on applicable margin upon achievement of certain leverage ratio				0.25%
Commitment fees on unused portion of facility				0.50%
Long term debt, outstanding amount				$ 311,300,000
Revolving Credit Facility [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				0.50%
Revolving Credit Facility [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				1.75%
Revolving Credit Facility [Member] | LIBOR Rate Loan [Member]
Debt Instrument [Line Items]
Applicable margin for Term Loans				2.75%
Revolving Credit Facility [Member] | LIBOR Rate Loan [Member] | Minimum
Debt Instrument [Line Items]
Debt instrument interest rate effective percentage				0.00%
Revolving Credit Facility [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Senior secured revolving								$ 210,000,000.0
Revolving Credit Facility [Member] | First-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Senior secured debt				$ 227,500,000
Revolving Credit Facility [Member] | Second-Priority Senior Secured Notes [Member]
Debt Instrument [Line Items]
Senior secured debt				$ 500,000,000.0
Long term debt, outstanding amount	$ 311,000,000.0
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
First lien secured net leverage ratio		625.00%
Restrictive covenants, description		The Revolving Credit Facility requires that the Company comply with a springing maximum first lien secured leverage ratio of 6.25x to be tested as of the last day of any fiscal quarter, solely to the extent that on such date the aggregate amount of funded loans and letters of credit (excluding undrawn letters of credit in an amount not to exceed $30.0 million and cash collateralized letters of credit) under the Revolving Credit Facility exceeds an amount equal to 35% of the then outstanding commitments under the Revolving Credit Facility. Pursuant to Amendment No. 12, among other terms, SEA will be exempt from complying with its first lien secured leverage ratio covenant through the end of 2021, after which SEA will be required to comply with such covenant starting in the first quarter of 2022. For purposes of calculating compliance with such covenant, unless a Triggering Event occurs (as defined in Amendment No. 12),  beginning with the first quarter of 2022, to the extent trailing Adjusted EBITDA (as defined in Amendment No. 12) for the second, third or fourth quarters of 2021 would have otherwise been included in the calculation of such covenant, in lieu of using actual Adjusted EBITDA for such periods, Adjusted EBITDA for such applicable periods will be deemed to be actual Adjusted EBITDA (as defined in Amendment No. 12) for the corresponding quarter of 2019.
Liquidity test commitment		$ 75,000,000.0
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Minimum
Debt Instrument [Line Items]
Minimum percentage of funded loan and letters of credit for covenant to apply		35.00%
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Excludable letters of credit under maximum required first lien secured leverage ratio		$ 30,000,000.0