Investment in Savoy (Condensed Balance Sheet - Savoy) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets	$ 64,867	$ 66,615
Other	20,745	11,416
Total assets	544,021	540,378
Total liabilities	325,690	333,558
Total liabilities and stockholders' equity	544,021	$ 540,378
Savoy [Member]
Current assets	7,617
Oil and gas properties, net	20,454
Other	1,003
Total assets	29,074
Total liabilities	3,789
Partners' capital	25,285
Total liabilities and stockholders' equity	$ 29,074