LONG-LIVED ASSET IMPAIRMENTS	12 Months Ended
Dec. 31, 2017
LONG-LIVED ASSET IMPAIRMENTS
LONG-LIVED ASSET IMPAIRMENTS	4. LONG-LIVED ASSET IMPAIRMENTS During the fourth quarter of 2015, the ARLP Partnership idled the Onton mine in response to market conditions and continued increases in coal inventories at the mines and customer locations. The ARLP Partnership's decision to idle this mine, as well as continued low coal prices and regulatory conditions led to the conclusion that indicators of impairment were present and the carrying value for certain mines may not be fully recoverable. During the ARLP Partnership's assessment of the recoverability of the carrying value of the ARLP Partnership's operating segments, they determined that they would likely not recover the carrying value of the net assets at MC Mining within the Appalachia segment and Onton within the Illinois Basin segment. Accordingly, the ARLP Partnership estimated the fair values of the MC Mining and Onton net assets and then adjusted the carrying values to the fair values resulting in impairments of $19.5 million and $66.9 million respectively. The fair value of the assets was determined using a market approach and represents a Level 3 fair value measurement under the fair value hierarchy. The fair value analysis was based on assumptions of marketability of coal properties in the current environment and the probability assessment of multiple sales scenarios based on observations of other mine sales. During the fourth quarter of 2015, the ARLP Partnership determined that certain undeveloped coal reserves and related property in western Pennsylvania were no longer a core part of the ARLP Partnership's foreseeable development plans and thus surrendered the lease for the properties in order to avoid the high holding costs of those reserves. The ARLP Partnership recorded an impairment charge of $3.0 million to the Appalachia segment during the quarter ended December 31, 2015 to remove advanced royalties associated with the lease from our consolidated balance sheet. During the third quarter of 2015, the ARLP Partnership surrendered a lease agreement for certain undeveloped coal reserves and related property in western Kentucky. The ARLP Partnership determined that coal reserves held under this lease agreement were no longer a core part of the ARLP Partnership's foreseeable development plans. As such, the ARLP Partnership surrendered the lease in order to avoid the high holding costs of those reserves. The ARLP Partnership recorded an impairment charge of $10.7 million to its Illinois Basin segment to remove certain assets associated with the lease, including mineral rights, advanced royalties and mining permits from our consolidated balance sheet. See Note 2 – Summary of Significant Accounting Policies for more information on our accounting policy for asset impairments.

4. LONG-LIVED ASSET IMPAIRMENTS

During the fourth quarter of 2015, the ARLP Partnership idled the Onton mine in response to market conditions and continued increases in coal inventories at the mines and customer locations. The ARLP Partnership's decision to idle this mine, as well as continued low coal prices and regulatory conditions led to the conclusion that indicators of impairment were present and the carrying value for certain mines may not be fully recoverable. During the ARLP Partnership's assessment of the recoverability of the carrying value of the ARLP Partnership's operating segments, they determined that they would likely not recover the carrying value of the net assets at MC Mining within the Appalachia segment and Onton within the Illinois Basin segment. Accordingly, the ARLP Partnership estimated the fair values of the MC Mining and Onton net assets and then adjusted the carrying values to the fair values resulting in impairments of $19.5 million and $66.9 million respectively.

The fair value of the assets was determined using a market approach and represents a Level 3 fair value measurement under the fair value hierarchy. The fair value analysis was based on assumptions of marketability of coal properties in the current environment and the probability assessment of multiple sales scenarios based on observations of other mine sales.

During the fourth quarter of 2015, the ARLP Partnership determined that certain undeveloped coal reserves and related property in western Pennsylvania were no longer a core part of the ARLP Partnership's foreseeable development plans and thus surrendered the lease for the properties in order to avoid the high holding costs of those reserves. The ARLP Partnership recorded an impairment charge of $3.0 million to the Appalachia segment during the quarter ended December 31, 2015 to remove advanced royalties associated with the lease from our consolidated balance sheet.

During the third quarter of 2015, the ARLP Partnership surrendered a lease agreement for certain undeveloped coal reserves and related property in western Kentucky. The ARLP Partnership determined that coal reserves held under this lease agreement were no longer a core part of the ARLP Partnership's foreseeable development plans. As such, the ARLP Partnership surrendered the lease in order to avoid the high holding costs of those reserves. The ARLP Partnership recorded an impairment charge of $10.7 million to its Illinois Basin segment to remove certain assets associated with the lease, including mineral rights, advanced royalties and mining permits from our consolidated balance sheet.

See Note 2 – Summary of Significant Accounting Policies for more information on our accounting policy for asset impairments.