Financial Instruments - Additional Information (Details)	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2021 USD ($) shares	Mar. 31, 2021 USD ($) Country	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Financial Instruments (Textual) [Abstract]
Cash and cash equivalents		$ 267,794,000	$ 317,379,000
Cash held outside of Canada		115,100,000	89,900,000
Transfers into/out of Level 3		$ 0	0
Number of countries that generate box office | Country		84
Foreign Exchange contract settlement date range		settlement dates throughout 2021
Estimated gains to be reclassified to earnings within the next twelve months		$ 1,700,000
Investment in equity securities		1,086,000	13,633,000
Investment in equity securities - cost		$ 15,200,000
Equity securities restrictions		lock-up period of six months
Fixed Income Securities [Member]
Financial Instruments (Textual) [Abstract]
Equity Investment, Debt Securities		$ 1,100,000	1,100,000
Preferred Stock [Member] | Other Assets [Member]
Financial Instruments (Textual) [Abstract]
Investment in equity securities		$ 1,000,000.0	1,000,000.0
Maoyan [Member]
Financial Instruments (Textual) [Abstract]
Investment in equity securities			12,600,000	$ 4,500,000
Number of shares sold | shares	7,949,000
Gross proceeds from sale of investment	$ 17,800,000
Gain relating to acquisition cost	2,600,000
Realized gain on fair value of investment	$ 5,200,000
Maximum [Member]
Financial Instruments (Textual) [Abstract]
Equity securities percentage ownership		1.00%
Republic of China [Member]
Financial Instruments (Textual) [Abstract]
Cash held/undistributed earnings		$ 84,200,000	$ 76,700,000