Equity method and other investments Equity Method and Other Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	$ 225,677	$ 224,611
Adjusted cost method investments
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	10,448	12,386
Other equity method partnerships
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	90,736	83,052
APAC joint venture
Schedule of Equity Method Investments [Line Items]
Equity method and other investments	$ 124,493	$ 129,173