Debt (Tables)

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Approximate Fair Value and Related Carrying Value of Long-term Debt, Including Current Maturities

The approximate fair value and related carrying value of the Company's total long-term debt, including current maturities of long-term debt presented as short-term debt, as of March 31, 2018 and December 31, 2017 were as follows:

In millions	March 31, 2018		December 31, 2017
Fair value	$	7,945	$	8,052
Carrying value	7,539		7,479