Guarantees (Tables)
 9 Months Ended
Sep. 30, 2017
Service and Product Warranties and Product Performance Guarantees [Abstract]  
Product Warranty Disclosure [Table Text Block]
The changes in the carrying amount of service and product warranties and product performance guarantees for the nine months ended September 30, 2017 and 2016 are as follows:
(Dollars in millions)
 
2017
 
2016
Balance as of January 1
 
$
1,199

 
$
1,212

Warranties and performance guarantees issued
 
221

 
218

Settlements made
 
(194
)
 
(192
)
Other
 
21

 
—

Balance as of September 30
 
$
1,247

 
$
1,238