Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments

Summary of the amortized cost and estimated fair value of short-term investments classified as trading securities

	December 31, 2017				December 31, 2016
	Amortized		Fair		Amortized		Fair
(Millions of dollars)	Cost		Value		Cost		Value
Domestic equity securities		619		752		444		482
Domestic debt securities held in mutual funds/ETFs/U.S. Treasuries		438		439		437		437
Foreign equity securities		266		319		198		199
Collateralized loan obligations		29		29		25		26
High yield securities		20		21		114		115
Money market funds held in trading accounts		10		10		13		13
Other trading securities		5		6		5		5
Total trading short-term investments	$	1,387	$	1,576	$	1,236	$	1,277