Investments Equity Method Investments Table (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments [Abstract]
Income on equity investments, net, before amortization of basis difference	$ 65,037	$ 53,311	$ 116,643	$ 106,199
Amortization of basis difference	(12,469)	(12,550)	(24,938)	(28,401)
Income on equity investments, net	$ 52,568	$ 40,761	$ 91,705	$ 77,798