Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Financial instruments measured at fair value on a recurring basis as of December 31, 2017 are as follows (in millions):

	Level 1		Level 2		Level 3		Total
Assets at fair value:
U.S. Treasury and Other Foreign Government Securities	$	734	$	—	$	—	$	734
Mutual Funds	16		—		—		16
Total assets at fair value	$	750	$	—	$	—	$	750

Financial instruments measured at fair value on a recurring basis as of December 31, 2016 are as follows (in millions):

	Level 1		Level 2		Level 3		Total
Assets at fair value:
Long-term Investment in Equity Securities	$	432	$	—	$	—	$	432
U.S. Treasury and Other Foreign Government Securities	500		—		—		500
Mutual Funds	23		—		—		23
Total assets at fair value	$	955	$	—	$	—	$	955