Debt (Tables)

12 Months Ended

Dec. 31, 2011

Debt [Abstract]

Schedule of long-term debt

	December 31
Millions of dollars	2011		2010
6.15% senior notes due September 2019	$	997	$	997
7.45% senior notes due September 2039		995		995
6.7% senior notes due September 2038		800		800
3.25% senior notes due November 2021		498		-
4.5% senior notes due November 2041		498		-
5.9% senior notes due September 2018		400		400
7.6% senior debentures due August 2096		293		293
8.75% senior debentures due February 2021		184		184
Other		155		155
Total long-term debt (due 2017 and thereafter)	$	4,820	$	3,824