Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Depreciation expense					$ 46,500	$ 45,600	$ 45,800
Property and equipment purchased through accounts payable and accrued liabilities, increased/decreased amount					6,900	4,200	1,900
Impairment charges (recoveries)	$ 676	$ 114,020	$ 88,380	$ 5,346	203,076	$ 5,346	$ (35)
Capitalized Software
Property Plant And Equipment [Line Items]
Impairment charges (recoveries)					$ 1,600
Audio Visual
Property Plant And Equipment [Line Items]
Impairment charges (recoveries)				$ 3,800