Supplemental Balance Sheet Information

INVENTORIES

Total inventories consisted of the following:



(millions)	June 30, 2015		December 31, 2014
Finished goods	$	218	$	232
Work in progress	36		35
Raw materials	70		62
Total	$	324	$	329

ASSET RETIREMENT OBLIGATIONS

Changes in the liability for asset retirement obligations consisted of the following:



	Six months ended June 30,
(millions)	2015			2014
Balance as of January 1	$	123		$	132
Accretion expense	4			4
Liabilities incurred	—			—
Changes in estimated cash flows (a)	(1		)	(10		)
Liabilities settled	(1		)	(2		)
Foreign currency translation	(2		)	(1		)
Balance as of June 30	$	123		$	123

(a)

Changes in estimated cash flows for the six months ended June 30, 2014 included changes in estimates primarily for our gypsum quarry and ship loading facility in Windsor, Nova Scotia, Canada, which we permanently closed during the third quarter of 2011, and our mining operation in Little Narrows, Nova Scotia, Canada as a result of receiving regulatory approval of a revised reclamation plan in 2014.

ACCRUED INTEREST

Interest accrued on our debt as of both June 30, 2015 and December 31, 2014 was $45 million and is included in accrued expenses on our accompanying consolidated balance sheets.

ASSETS HELD FOR SALE

As of June 30, 2015, assets held for sale totaled $42 million, which included port facilities in Mexico and our investment in the Knauf USG joint venture. As of December 31, 2014, assets held for sale totaled $5 million, which reflected other indefinite-lived intangible assets. Assets held for sale are classified as other current assets in our accompanying consolidated balance sheets.

In June 2014, we sold surplus property for a gain of $12 million which is included in cost of goods in our statement of operations.