Goodwill and Intangible Assets

The Partnership's intangible assets consist of the following (in thousands):



	December 31, 2015			December 31, 2014
Contract intangibles	$	81,109		$	82,972
Other intangibles	5,076			3,004
Less accumulated amortization	(29,258		)	(25,243		)
Total intangible assets, net	$	56,927		$	60,733

Amortization expense related to the Partnership's intangible assets totaled $4.6 million, $3.6 million and $3.8 million for the years ended December 31, 2015, 2014 and 2013, respectively.

During the second quarter of 2014, the Partnership and a lessee amended an aggregates lease in its Coal, Hard Mineral Royalty and Other segment, which led the Partnership to conclude an impairment triggering event had occurred. Fair value of the lease agreement was determined using Level 3 expected cash flows. The resulting impairment expense of $5.6 million is included in Asset impairments on the Consolidated Statements of Comprehensive Income.

The estimates of amortization expense for the periods as indicated below are based on current mining plans and are subject to revision as those plans change in future periods.



For the Year Ended December 31,	Estimated Amortization Expense
	(in thousands)
2016	$	3,544
2017	3,095
2018	3,108
2019	3,108
2020	3,108

The weighted average remaining amortization period for contract intangibles and other intangibles was 14 years and 31 years, respectively.

During the fourth quarter of 2014, $52.0 million of goodwill was added relating to the VantaCore acquisition. This amount represented the preliminary residual value. During 2015, the purchase price allocation was adjusted as more detailed analysis was completed and additional information was obtained about the facts and circumstances for VantaCore’s property, plant and equipment, right to mine assets and asset retirement obligations that existed as of the acquisition date. These adjustments decreased goodwill by $46.5 million and resulted in an acquisition date goodwill of $5.5 million.

During the fourth quarter of 2015, we evaluated goodwill for impairment and compared the estimated fair value of the VantaCore reporting unit to its carrying amount. The carrying amount exceeded fair value and we recorded a $5.5 million goodwill impairment expense. The lower fair value was primarily a result of the deterioration in certain regional markets in which VantaCore operates causing a decline in future performance levels compared to levels estimated during the purchase price allocation process. A discounted cash flow model was used to estimate fair value. Significant inputs used to determine fair value include estimates of future cash flow, discount rate and useful economic life. These estimates were based on current conditions and historical experience applied to develop projections of future operating performance.