Investments and other assets - Components of Investments and Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Investments, All Other Investments [Abstract]
Cash value life insurance	$ 51,797	$ 52,462
Equity method investments	35,084	27,650
Other equity investments	28,124	32,383
Deferred debt issuance costs	11,180	10,921
Other long-term assets	21,846	21,853
Total	$ 148,031	$ 145,269