Operating Segment and Enterprise Wide Reporting (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Information about Reportable Segments

The following tables present information about reportable segments (in thousands):

						Project
	Product		Research			Consulting		Consolidated
Year Ended December 31, 2017
Research services revenues	$	216,471	$	—		$	—	$	216,471
Advisory services and events revenues		21,887		45,054			54,261		121,202
Total segment revenues		238,358		45,054			54,261		337,673
Segment expenses		45,205		48,812			25,477		119,494
Contribution margin (loss)		193,153		(3,758	)		28,784		218,179
Selling, marketing, administrative and other expenses									(189,849	)
Amortization of intangible assets									(781	)
Reorganization costs									—
Other income and losses on investments									(178	)
Income before income taxes								$	27,371

						Project
	Product		Research			Consulting		Consolidated
Year Ended December 31, 2016
Research services revenues	$	215,216	$	—		$	—	$	215,216
Advisory services and events revenues		20,374		44,631			45,874		110,879
Total segment revenues		235,590		44,631			45,874		326,095
Segment expenses		41,528		47,496			23,141		112,165
Contribution margin (loss)		194,062		(2,865	)		22,733		213,930
Selling, marketing, administrative and other expenses									(181,299	)
Amortization of intangible assets									(831	)
Reorganization costs									(1,026	)
Other income and losses on investments									(65	)
Income before income taxes								$	30,709

						Project
	Product		Research			Consulting		Consolidated
Year Ended December 31, 2015
Research services revenues	$	210,268	$	—		$	—	$	210,268
Advisory services and events revenues		17,512		42,422			43,524		103,458
Total segment revenues		227,780		42,422			43,524		313,726
Segment expenses		38,615		48,277			23,292		110,184
Contribution margin (loss)		189,165		(5,855	)		20,232		203,542
Selling, marketing, administrative and other expenses									(179,391	)
Amortization of intangible assets									(891	)
Reorganization costs									(4,433	)
Other income and losses on investments									493
Income before income taxes								$	19,320

Schedule of Net Long-lived Tangible Assets by Location

Net long-lived tangible assets by location as of December 31, 2017 and 2016 are as follows (in thousands):

	2017		2016
United States	$	23,943	$	22,150
United Kingdom		727		782
Europe (excluding United Kingdom)		163		259
Other		416		703
Total	$	25,249	$	23,894

Schedule of Revenues by Geographic Destination and as a Percentage of Total Revenues

Revenues by geographic destination and as a percentage of total revenues for the years ended December 31, 2017, 2016, and 2015 are as follows (dollars in thousands):

	2017		2016		2015
United States	$	260,077	$	252,222	$	241,025
Europe (excluding United Kingdom)		28,525		27,061		24,607
United Kingdom		13,651		14,808		16,815
Canada		14,523		13,806		14,424
Other		20,897		18,198		16,855
Total	$	337,673	$	326,095	$	313,726

	2017			2016			2015
United States		77	%		77	%		77	%
Europe (excluding United Kingdom)		9			8			8
United Kingdom		4			5			5
Canada		4			4			5
Other		6			6			5
Total		100	%		100	%		100	%