XML 100 R59.htm IDEA: XBRL DOCUMENT v3.8.0.1
Summary Of Significant Accounting Policies (Materials And Supplies Fuel Stock And Natural Gas Stored) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Accounting Policies [Abstract]    
Materials and supplies $ 41,493 $ 40,700
Fuel stock 4,843 4,585
Stored natural gas 11,739 8,029
Total $ 58,075 $ 53,314