Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2016

Investments, Debt and Equity Securities [Abstract]

Marketable Securities [Table Text Block]

	Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(In millions)
June 30, 2016
United States government obligations
Maturity less than 1 year	$	356	$	—	$	—		$	356
Maturity 1 to 5 years	115		1		—			116
Corporate debt securities
Maturity less than 1 year	1		—		—			1
Maturity 1 to 5 years	69		2		—			71
Other debt securities
Maturity less than 1 year	39		—		—			39
Equity securities
Available-for-sale	300		4		(4		)	300
	$	880	$	7	$	(4	)	$	883

	Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(In millions)
December 31, 2015
United States government obligations
Maturity less than 1 year	$	256	$	—	$	—		$	256
Maturity 1 to 5 years	116		—		—			116
Corporate debt securities
Maturity 1 to 5 years	26		—		—			26
Other debt securities
Maturity less than 1 year	182		—		—			182
Maturity 1 to 5 years	3		—		—			3
Equity securities
Available-for-sale	296		4		(6		)	294
	$	879	$	4	$	(6	)	$	877