XML 91 R59.htm IDEA: XBRL DOCUMENT v3.8.0.1
Intangible Assets, Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Sep. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Goodwill        
Loss on impairment $ 370 $ 370 $ 0  
Goodwill   $ 0 $ 370 $ 370