Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of Marketable Securities [Table Text Block]

	June 30, 2017						December 31, 2016
	Cost		Unrealized Gain (Loss)		Fair Value		Cost		Unrealized Gain (Loss)		Fair Value
U.S. government securities	$	3	$	—	$	3	$	2	$	—	$	2
Corporate securities	5				5		2				2
Certificates of deposit	23				23		22				22
Other	5				5		4				4
Total marketable securities	$	36	$	—	$	36	$	30	$	—	$	30