Postretirement Benefit Plans (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block
Other postretirement benefit expense	$ 1
Amortization of net actuarial loss (less than $1 million)	(1)
Employer contribution to defined benefit plan	8	$ 6
Minimum
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block
Additional contributions	18
Maximum
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block
Additional contributions	$ 28