Debt

12 Months Ended

Dec. 31, 2011

Debt [Abstract]

Debt

Note 6. Debt

Long-term debt consisted of the following:

	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

Senior debt

All of our senior notes and debentures rank equally with our existing and future senior unsecured indebtedness, have semiannual interest payments, and no sinking fund requirements. We may redeem all of our senior notes from time to time or all of the notes of each series at any time at the applicable redemption prices, plus accrued and unpaid interest. Our 7.6% and 8.75% senior debentures may not be redeemed prior to maturity.

Revolving credit facilities

In February 2011, we entered into a new unsecured $2.0 billion five-year revolving credit facility that replaced our then existing $1.2 billion unsecured credit facility established in July 2007. The purpose of the facility is to provide general working capital and credit for other corporate purposes. The full amount of the revolving credit facility was available as of December 31, 2011.