Investments and other assets - Components of Investments and Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments, All Other Investments [Abstract]
Available-for-sale debt security	$ 57,354	$ 3,000
Cash value life insurance	52,861	52,883
Equity method investments	25,504	32,067
Other equity investments	19,021	20,271
Deferred debt issuance costs	6,706	9,378
Other long-term assets	23,427	18,620
Total	$ 184,873	$ 136,219