Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Trading Securities [Table Text Block]

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

	December 31, 2017		December 31, 2016
Debt securities	$	43	$	47
Equity securities	54		60
Total	$	97	$	107