16. Segments

The following table presents the Company’s operations by reportable segment. The Company is managed through two reportable segments, Product Development and Integrated Healthcare Services. Product Development, which primarily serves biopharmaceutical clients engaged in research and development, provides clinical research and clinical trial services. Integrated Healthcare Services provides commercialization services to biopharmaceutical clients and research, analytics, real-world and late phase research, and other services to both biopharmaceutical clients and the broader healthcare market.

Certain costs are not allocated to the Company’s segments and are reported as general corporate and unallocated expenses. These costs primarily consist of stock-based compensation, and expenses for corporate overhead functions such as senior leadership, finance, human resources, information technology, facilities and legal. The Company does not allocate restructuring costs, merger related costs or impairment charges to its segments. Information presented below is in thousands:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
Service revenues
Product Development	$	874,312		$	810,045		$	2,601,909		$	2,345,971
Integrated Healthcare Services		262,111			283,435			809,600			851,849
Total service revenues		1,136,423			1,093,480			3,411,509			3,197,820
Costs of revenue, service costs
Product Development		499,638			461,858			1,513,353			1,352,730
Integrated Healthcare Services		204,153			221,200			631,643			676,000
Total costs of revenue, service costs		703,791			683,058			2,144,996			2,028,730
Selling, general and administrative expenses
Product Development		167,732			166,758			505,378			478,643
Integrated Healthcare Services		35,172			38,186			111,422			114,953
General corporate and unallocated		30,741			26,471			83,987			83,323
Total selling, general and administrative expenses		233,645			231,415			700,787			676,919
Income from operations
Product Development		206,942			181,429			583,178			514,598
Integrated Healthcare Services		22,786			24,049			66,535			60,896
General corporate and unallocated		(30,741	)		(26,471	)		(83,987	)		(83,323	)
Restructuring costs		467			(11,984	)		(27,791	)		(23,542	)
Merger related costs		(3,747	)		—			(12,689	)		—
Impairment charges		(27,937	)		—			(27,937	)		—
Total income from operations	$	167,770		$	167,023		$	497,309		$	468,629

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Depreciation and amortization expense
Product Development	$	29,593	$	26,681	$	82,575	$	74,110
Integrated Healthcare Services		4,020		5,118		12,549		15,497
General corporate and unallocated		990		1,085		3,244		3,617
Total depreciation and amortization expense	$	34,603	$	32,884	$	98,368	$	93,224