XML 83 R63.htm IDEA: XBRL DOCUMENT v3.10.0.1
Contingencies - Environmental Contingencies (Details)
6 Months Ended
Jun. 30, 2018
USD ($)
Commitments and Contingencies Disclosure [Abstract]  
Environmental liability insurance, maximum coverage per incident (up to) $ 10,000,000
Environmental liability insurance, annual coverage limit (up to) $ 50,000,000