Shareholders' Equity

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note [Abstract]

Shareholders' Equity

Shareholders’ Equity

Shares of common stock

The following table summarizes total shares of common stock outstanding:

	December 31
Millions of shares	2015		2014
Issued	1,071		1,071
In treasury	(215	)	(223	)
Total shares of common stock outstanding	856		848

Our Board of Directors has authorized a program to repurchase our common stock from time to time. The program does not require a specific number of shares to be purchased and the program may be effected through solicited or unsolicited transactions in the market or in privately negotiated transactions. The program may be terminated or suspended at any time. There were no repurchases made under the program during the year ended December 31, 2015. Approximately $5.7 billion remains authorized for repurchases as of December 31, 2015. From the inception of this program in February 2006 through December 31, 2015, we repurchased approximately 201 million shares of our common stock for a total cost of approximately $8.4 billion.

Preferred stock

Our preferred stock consists of five million total authorized shares at December 31, 2015, of which none are issued.

Accumulated other comprehensive loss

Accumulated other comprehensive loss consisted of the following:

	December 31
Millions of dollars	2015			2014
Defined benefit and other postretirement liability adjustments (a)	$	(221	)	$	(326	)
Cumulative translation adjustment	(78		)	(70		)
Unrealized loss on cash flow hedge	(67		)	—
Other	3			(3		)
Total accumulated other comprehensive loss	$	(363	)	$	(399	)

(a) Included net actuarial losses for our international pension plans of $205 million at

December 31, 2015 and $298 million at December 31, 2014.