Investments in debt and equity securities (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale securities

The cost basis and fair value of debt and equity securities were as follows:

	December 31, 2016							December 31, 2015
(Millions of dollars)	Cost Basis		Unrealized Pretax Net Gains (Losses)			Fair Value		Cost Basis		Unrealized Pretax Net Gains (Losses)		Fair Value
Government debt
U.S. treasury bonds	$	9	$	—		$	9	$	9	$	—	$	9
Other U.S. and non-U.S. government bonds	60		—			60		71		1		72
Corporate bonds
Corporate bonds	489		3			492		701		7		708
Asset-backed securities	90		—			90		129		—		129
Mortgage-backed debt securities
U.S. governmental agency	225		(2		)	223		291		1		292
Residential	10		—			10		12		—		12
Commercial	36		—			36		59		2		61
Equity securities
Large capitalization value	280		32			312		243		30		273
Real estate investment trust (REIT)	77		2			79		25		—		25
Smaller company growth	41		15			56		37		17		54
Total	$	1,317	$	50		$	1,367	$	1,577	$	58	$	1,635

Investments in an unrealized loss position that are not other-than-temporarily impaired

Available-for-sale investments in an unrealized loss position that are not other-than-temporarily impaired:
	December 31, 2016
	Less than 12 months 1				12 months or more 1				Total
(Millions of dollars)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds
Corporate bonds	$	131	$	1	$	13	$	—	$	144	$	1
Mortgage-backed debt securities
U.S. governmental agency	167		2		11		—		178		2
Equity securities
Large capitalization value	68		6		11		2		79		8
Smaller company growth	10		1		3		1		13		2
Total	$	376	$	10	$	38	$	3	$	414	$	13

	December 31, 2015
	Less than 12 months 1				12 months or more 1				Total
(Millions of dollars)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds
Corporate bonds	$	242	$	3	$	27	$	1	$	269	$	4
Asset-backed securities	84		1		10		1		94		2
Mortgage-backed debt securities
U.S. governmental agency	135		1		57		1		192		2
Equity securities
Large capitalization value	97		8		2		—		99		8
Smaller company growth	14		1		—		—		14		1
Total	$	572	$	14	$	96	$	3	$	668	$	17

¹  Indicates length of time that individual securities have been in a continuous unrealized loss position.

Cost basis and fair value of the available-for-sale debt securities by contractual maturity

	December 31, 2016
(Millions of dollars)	Cost Basis		Fair Value
Due in one year or less	$	188	$	189
Due after one year through five years	421		423
Due after five years through ten years	13		13
Due after ten years	26		26
U.S. governmental agency mortgage-backed securities	225		223
Residential mortgage-backed securities	10		10
Commercial mortgage-backed securities	36		36
Total debt securities – available-for-sale	$	919	$	920

Schedule of proceeds and gross gain and losses from the sale of available-for-sale securities

Sales of Securities:
	Years Ended December 31,
(Millions of dollars)	2016		2015		2014
Proceeds from the sale of available-for-sale securities	$	694	$	351	$	434
Gross gains from the sale of available-for-sale securities	$	55	$	64	$	38
Gross losses from the sale of available-for-sale securities	$	4	$	2	$	2