Equity method and other investments Equity Method and Other Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	$ 226,309	$ 224,611
Adjusted cost method investments
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	12,386	12,386
Other Ownership Interest
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	88,861	83,052
Deconsolidated Noncontrolling Entity
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	$ 125,062	$ 129,173