Supplemental Balance Sheet Information

INVENTORIES

Total inventories consisted of the following:



(millions)	March 31, 2015		December 31, 2014
Finished goods	$	235	$	232
Work in progress	37		35
Raw materials	56		62
Total	$	328	$	329

ASSET RETIREMENT OBLIGATIONS

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



	Three months ended March 31,
(millions)	2015			2014
Balance as of January 1	$	123		$	132
Accretion expense	2			2
Liabilities incurred	—			—
Changes in estimated cash flows (a)	—			(10		)
Liabilities settled	—			(2		)
Foreign currency translation	(3		)	(2		)
Balance as of March 31	$	122		$	120

(a)

Changes in estimated cash flows for the three months ended March 31, 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 March 31, 2015 and December 31, 2014 was $36 million and $45 million, respectively, and is included in accrued expenses on our accompanying consolidated balance sheets.

ASSETS HELD FOR SALE

Assets held for sale as of March 31, 2015 totaled $35 million, which reflected the two self-unloading ocean vessels owned by Gypsum Transportation Limited, or GTL, and as of December 31, 2014 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. See Note 17 for discussion of GTL and a related subsequent event.