Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Research	$ 653,443	$ 466,877	$ 1,778,481	$ 1,371,157
Consulting	72,117	73,707	242,404	237,876
Events	44,953	33,475	171,427	132,290
Talent Assessment & Other	57,572	0	104,673	0
Total revenues	828,085	574,059	2,296,985	1,741,323
Costs and expenses:
Cost of services and product development	332,207	223,122	921,820	666,585
Selling, general and administrative	421,163	269,902	1,133,633	799,322
Depreciation	17,340	9,531	45,637	27,390
Amortization of intangibles	51,224	6,221	123,014	18,614
Acquisition and integration charges	30,500	16,557	142,104	32,958
Total costs and expenses	852,434	525,333	2,366,208	1,544,869
Operating (loss) income	(24,349)	48,726	(69,223)	196,454
Interest expense, net	(38,762)	(5,932)	(88,624)	(19,294)
Other income, net	1,171	1,954	1,653	5,086
(Loss) income before income taxes	(61,940)	44,748	(156,194)	182,246
(Benefit) provision for income taxes	(13,760)	14,264	(52,166)	55,149
Net (loss) income	$ (48,180)	$ 30,484	$ (104,028)	$ 127,097
Net (loss) income per share:
Basic (in dollars per share)	$ (0.53)	$ 0.37	$ (1.19)	$ 1.54
Diluted (in dollars per share)	$ (0.53)	$ 0.36	$ (1.19)	$ 1.52
Weighted average shares outstanding:
Basic (in shares)	90,624	82,638	87,585	82,549
Diluted (in shares)	90,624	83,803	87,585	83,761