Investments (Tables)

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Trading Securities [Table Text Block]

The following table summarizes the fair value of investments held as of September 30, 2017 and December 31, 2016 (in millions):

	September 30, 2017		December 31, 2016
Debt securities	$	42	$	47
Equity securities	60		60
Total	$	102	$	107

Realized Gain (Loss) on Investments [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Gains	$	3	$	4	$	10	$	11
Losses	—		—		—		(4		)
Net Gain	$	3	$	4	$	10	$	7