Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2019

Marketable Securities.

Schedule of marketable securities

(Millions)	March 31, 2019		December 31, 2018
Corporate debt securities	$	16	$	—
Commercial paper		510		366
Certificates of deposit/time deposits		10		10
U.S. municipal securities		3		3
Asset-backed securities		—		1
Current marketable securities	$	539	$	380
U.S. municipal securities	$	46	$	37
Non-current marketable securities	$	46	$	37
Total marketable securities	$	585	$	417

Marketable securities by contractual maturity

(Millions)	March 31, 2019
Due in one year or less	$	539
Due after one year through five years		13
Due after five years through ten years		24
Due after ten years		9
Total marketable securities	$	585