Equity Investees (Schedule of Balance Sheet Information for Equity Investees) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Current assets	$ 15,895	$ 18,711
Fixed assets, net	205,785	217,343
Other assets	966	1,203
Total assets	222,646	237,257
Liabilities and equity
Current liabilities	17,644	17,560
Other liabilities	243,608	237,434
Equity	(38,606)	(17,737)
Total liabilities and equity	$ 222,646	$ 237,257