Goodwill and Identifiable Assets (Tables)

3 Months Ended

Mar. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

The changes in the carrying amount of goodwill for the year ended December 31, 2015 and the three months ended March 31, 2016 are as follows (in thousands):



	Apex Segment			Oxford Segment			Total
Balance as of December 31, 2014	$	287,951		$	224,109		$	512,060
Creative Circle Acquisition	358,029			—			358,029
LabResource Acquisition	—			6,449			6,449
Translation adjustment	(1,363		)	(269		)	(1,632		)
Balance as of December 31, 2015	644,617			230,289			874,906
Translation adjustment	355			396			751
Balance as of March 31, 2016	$	644,972		$	230,685		$	875,657

Schedule of Acquired Intangible Assets

Acquired intangible assets consisted of the following (in thousands):



		As of March 31, 2016						As of December 31, 2015
	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Subject to amortization:
Customer relationships	2 - 10 years	$	196,780	$	80,781	$	115,999	$	196,472	$	74,640	$	121,832
Contractor relationships	2 - 5 years	69,813		42,991		26,822		69,764		40,124		29,640
Non-compete agreements	2 - 7 years	10,889		3,626		7,263		10,874		3,163		7,711
In-use software	6 years	18,900		7,304		11,596		18,900		6,516		12,384
Favorable contracts	5 years	900		242		658		900		172		728
		297,282		134,944		162,338		296,910		124,615		172,295
Not subject to amortization:
Trademarks		245,761		—		245,761		245,630		—		245,630
Total		$	543,043	$	134,944	$	408,099	$	542,540	$	124,615	$	417,925

Schedule of Estimated Future Amortization Expense

Estimated amortization expense for the remainder of this year, each of the next four years, and thereafter is as follows (in thousands):



2016	$	29,515
2017	33,054
2018	28,928
2019	22,016
2020	14,515
Thereafter	34,310
	$	162,338