Investments (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of maturities for short-term investments

The estimated fair values of short-term investments, which approximate cost at December 31, 2018, are shown below by contractual maturity. Actual maturities may differ from contractual maturities because issuers of certain securities have the right to retire our investments without prepayment penalties.

(in millions)
Due in one year or less	$	93
Due after one year through three years	96
Due after three years through five years	1
Due after five years	13
Total	$	203