Investments (Tables)

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Maturities for short-term investments

The estimated fair values of short-term investments, which approximate cost at June 30, 2017, are shown below by contractual maturity. Actual maturities may differ from contractual maturities because issuers of the securities may have the right to retire our investments without prepayment penalties. Investments with maturities beyond one year when purchased may be classified as short-term investments if they are expected to be available to support our short-term liquidity needs.

(in millions)	Available-For-Sale
Due in one year or less	$	239
Due after one year through three years	438
Due after three years through five years	51
Due after five years	19
Total	$	747