(7) Goodwill and Intangible Assets

There were no changes in goodwill for the three months ended March 31, 2016. Goodwill by operating segment is as follows (in thousands):

	Supply Chain Management		IT, Energy and Management Consulting		Aviation		Total
Balance as of December 31, 2015	$	63,113	$	30,883	$	104,549	$	198,545

Balance as of March 31, 2016	$	63,113	$	30,883	$	104,549	$	198,545

Intangible assets consist of the value of contract-related assets, acquired technologies and trade names. Amortization expense was approximately $4 million and $3.6 million for the three months ended March 31, 2016 and 2015, respectively.

Intangible assets were comprised of the following (in thousands):

	Cost		Accumulated Amortization			Accumulated Impairment Loss			Net Intangible Assets
March 31, 2016
Contract and customer-related	$	173,084	$	(49,911	)	$	(1,025	)	$	122,148
Acquired technologies		12,400		(5,432	)		-			6,968
Trade names – amortizable		16,730		(6,823	)		-			9,907
Total	$	202,214	$	(62,166	)	$	(1,025	)	$	139,023

December 31, 2015
Contract and customer-related	$	173,084	$	(46,611	)	$	(1,025	)	$	125,448
Acquired technologies		12,400		(5,151	)		-			7,249
Trade names		16,730		(6,384	)		-			10,346
Total	$	202,214	$	(58,146	)	$	(1,025	)	$	143,043