Employees Pension and Postretirement Benefits - Additional Information (Details) - USD ($)		3 Months Ended		12 Months Ended
	Nov. 01, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Deferred Compensation Plan [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Deferred compensation plan description		The Company maintained a nonqualified deferred compensation benefit plan (the “Retirement Plan”) covering the former CEO of IMAX Entertainment and Senior Executive Vice President of the Company. Under the terms of the Retirement Plan, the benefits were due to vest in full if the executive incurred a separation from service from the Company (as defined therein).
Deferred Compensation Plan [Member] | Accrued and Other Liabilities [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Benefit obligation recorded		$ 3,700,000		$ 3,700,000
Deferred Compensation Plan [Member] | Prepaid Expenses [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Company-owned life insurance		$ 3,200,000		3,200,000
Richard L. Gelfond [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Benefit payable	$ 20,300,000
SERP Benefits [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Defined benefit pension plan		The Company has an unfunded defined benefit pension plan, the Supplemental Executive Retirement Plan (the “SERP”), covering its CEO, Richard L.
Benefit Obligation		$ 20,134,000		20,116,000	$ 18,840,000
Interest costs		18,000		379,000
Expected interest costs in the remainder of the year		100,000
Companies contribution and expenses during the remainder of 2020		0
SERP Benefits [Member] | Maximum [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Interest costs		$ 100,000	$ 100,000
Defined Contribution Plan [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Defined contribution pension plans for employees		The Company also maintains defined contribution plans for its employees, including its executive officers. The Company makes contributions to these plans on behalf of employees in an amount up to 5% of their base salary subject to certain prescribed maximums.
Maximum percentage of base salary contributed to Defined Contribution Pension Plan by Company		5.00%
Canadian Plan [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Contribution and recorded expense		$ 300,000	300,000
Us Internal Revenue Code [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Contribution and recorded expense		200,000	200,000
Postretirement Benefits Executives [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Benefit Obligation		700,000		700,000
Postretirement Benefits Executives [Member] | Maximum [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Maximum amount of Postretirement benefit recorded expense		100,000	100,000
Postretirement Benefits Canadian Employees [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Benefit Obligation		1,800,000		$ 1,900,000
Postretirement Benefits Canadian Employees [Member] | Maximum [Member]
Pension and Other Postretirement Benefit Expense (Textual) [Abstract]
Maximum amount of Postretirement benefit recorded expense		$ 100,000	$ 100,000