Equity Investees (Schedule of Balance Sheet Information for Equity Investees) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Current assets	$ 13,626	$ 18,711
Fixed assets, net	213,472	217,343
Other assets	1,123	1,203
Total assets	228,221	237,257
Liabilities and equity
Current liabilities	17,846	17,560
Other liabilities	235,834	237,434
Equity	(25,459)	(17,737)
Total liabilities and equity	$ 228,221	$ 237,257