Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2016

Line of Credit Facility [Abstract]

Schedule of Short-term Debt [Table Text Block]

Short-term borrowings under these credit facilities and related interest rates were as follows (dollars in millions):

	Years Ended December 31,
	2016			2015			2014
Average daily amount of short-term debt outstanding	$	1		$	—		$	—
Weighted daily average interest rate *	0.7		%	0.6		%	—		%
Maximum amount outstanding during the year	$	23		$	11		$	—

* Excludes the effect of commitment fees, facility fees and other financing fees.