Long-Term Debt - Additional Information (Detail)				3 Months Ended			9 Months Ended
	Oct. 31, 2018 USD ($)	Jan. 05, 2018 USD ($)	Jan. 03, 2017 USD ($)	Sep. 30, 2018 USD ($) Swap	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2018 USD ($) Swap	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 1,527,266,000			$ 1,527,266,000		$ 1,560,046,000
Outstanding letters of credit				$ 21,300,000			$ 21,300,000
Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Number of interest rate swaps held | Swap				5			5
Notional amount of interest rate swap				$ 1,000,000,000			$ 1,000,000,000
Maturity of interest rate swap							May 14, 2020
Weighted average fixed interest rate				2.45%			2.45%
Variable rate of interest				0.75%			0.75%
Variable rate of interest, description							variable rate of interest based upon the greater of 0.75% or the BBA LIBOR
Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Percentage of annual excess cash flow used to prepay outstanding loan							50.00%
Percentage of net proceeds from sale of non-ordinary assets				100.00%			100.00%
Percentage of net proceeds incurrence of debt							100.00%
Mandatory prepayments						$ 6,300,000
Cash paid for interest		$ 5,100,000	$ 12,900,000				$ 61,800,000	$ 67,300,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs and discounts				$ 1,600,000			1,600,000		2,500,000
Senior secured revolving				210,000,000			210,000,000
Long-term debt									15,000,000
Amount available for borrowing				188,700,000			$ 188,700,000
Revolving Credit Facility [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Senior secured revolving	$ 210,000,000
Debt instrument maturity date	Oct. 31, 2023
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Restrictive covenants, description							The Senior Secured Credit Facilities permit restricted payments in an aggregate amount per annum equal to the sum of (A) $25.0 million plus (B) an amount, if any, equal to (1) if the total net leverage ratio on a pro forma basis after giving effect to the payment of any such restricted payment, is no greater than 3.50 to 1.00, an unlimited amount, (2) if the total net leverage ratio on a pro forma basis after giving effect to the payment of any such restricted payment is no greater than 4.00 to 1.00 and greater than 3.50 to 1.00, the greater of (a) $95.0 million and (b) 7.50% of Market Capitalization (as defined in the Senior Secured Credit Facilities), (3) if the total net leverage ratio on a pro forma basis after giving effect to the payment of any such restricted payment is no greater than 4.50 to 1.00 and greater than 4.00 to 1.00, $95.0 million and (4) if the total net leverage ratio on a pro forma basis after giving effect to the payment of any such restricted payment is no greater than 5.00 to 1.00 and greater than 4.50 to 1.00, $65.0 million.
Percentage of Market Capitalization on restricted payment							7.50%
First lien secured net leverage ratio							350.00%
Total net leverage ratio, as calculated							340.00%
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of annual excess cash flow used to prepay outstanding loan							25.00%
Restricted payment on Senior Secured Credit Facilities, base payment							$ 25,000,000
Restricted payment on Senior Secured Credit Facilities, first payment							95,000,000
Restricted payment on Senior Secured Credit Facilities, second payment							95,000,000
Restricted payment on Senior Secured Credit Facilities, third payment							$ 65,000,000
Total net leverage ratio, one							400.00%
Total net leverage ratio, two							450.00%
Total net leverage ratio, three							500.00%
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage of annual excess cash flow used to prepay outstanding loan							0.00%
Total net leverage ratio, one							350.00%
Total net leverage ratio, two							400.00%
Total net leverage ratio, three							450.00%
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
First lien secured net leverage ratio	625.00%
Restrictive covenants, description	The New Revolving Credit Facility requires that SEA 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 New Revolving Credit Facility exceeds an amount equal to 35% of the then outstanding commitments under the New Revolving Credit Facility.
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member] | Maximum [Member]
Debt Instrument [Line Items]
Excludable letters of credit under maximum required first lien secured leverage ratio	$ 30,000,000
Restrictive Covenants [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member] | Minimum [Member]
Debt Instrument [Line Items]
Minimum percentage of funded loan and letters of credit for covenant to apply	35.00%
Term B-5 Loans [Member]
Debt Instrument [Line Items]
Debt instrument, balance						$ 998,300,000
Discount initially recorded								5,000,000
Debt issuance costs initially recorded								40,000
Write-off of discounts and debt issuance costs								$ 8,000,000
Unamortized debt issuance costs and discounts				10,400,000			$ 10,400,000		11,900,000
Debt instrument maturity date							Mar. 31, 2024
Long-term debt				983,331,000			$ 983,331,000		990,819,000
Percent of original principal amount on effective date used to calculate aggregate annual amount which will amortize in equal quarterly installments						1.00%
Term B-5 Loans [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, balance	$ 543,900,000
Term B-2 Loans [Member]
Debt Instrument [Line Items]
Repayment of outstanding principal						$ 753,600,000
Unamortized debt issuance costs and discounts				2,200,000			$ 2,200,000		3,300,000
Debt instrument maturity date							May 14, 2020
Long-term debt				543,935,000			$ 543,935,000		$ 554,227,000
Cash paid for interest		$ 5,100,000
Term B-2 Loans [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Mandatory prepayments				0	$ 2,800,000		0
Term B-2 Loans [Member] | Senior Secured Credit Facilities [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Repayment of outstanding principal	$ 543,900,000
Term B-3 Loans [Member]
Debt Instrument [Line Items]
Repayment of outstanding principal						244,700,000
Term B-3 Loans [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Mandatory prepayments				$ 0			$ 0
Term B-2 and Term B-3 Loans [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Mandatory prepayments						$ 3,500,000