Revenue and Related Contract Costs and Contract Liabilities - Summary of Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Balance at January 1	$ 50,796	$ 35,600
Cash additions	154,057	210,871
Revenue recognized	(186,518)	(196,158)
Foreign exchange translation adjustment	283	483
Balance at December 31	$ 18,618	$ 50,796