Debt (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of long-term debt

	December 31
Millions of dollars	2015			2014
5.0% senior notes due November 2045	$	2,000		$	—
3.8% senior notes due November 2025	2,000			—
3.375% senior notes due November 2022	1,250			—
2.7% senior notes due November 2020	1,250			—
3.5% senior notes due August 2023	1,100			1,100
4.85% senior notes due November 2035	1,000			—
6.15% senior notes due September 2019	1,000			1,000
7.45% senior notes due September 2039	1,000			1,000
4.75% senior notes due August 2043	900			900
6.7% senior notes due September 2038	800			800
1.0% senior notes due August 2016	600			600
3.25% senior notes due November 2021	500			500
4.5% senior notes due November 2041	500			500
2.0% senior notes due August 2018	400			400
5.9% senior notes due September 2018	400			400
7.6% senior debentures due August 2096	300			300
8.75% senior debentures due February 2021	185			185
6.75% notes due February 2027	104			104
7.53% notes due May 2017	45			45
Other	144			37
Unamortized debt issuance costs and discounts	(132		)	(92		)
Total	15,346			7,779
Current maturities	(659		)	(14		)
Total long-term debt	$	14,687		$	7,765