Investments and other assets - Components of Investments and Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investments, All Other Investments [Abstract]
Cash value life insurance	$ 52,050	$ 52,462
Equity method investments	30,257	27,650
Other equity investments	28,124	32,383
Deferred debt issuance costs	10,279	10,921
Other long-term assets	22,496	21,853
Total	$ 143,206	$ 145,269