Operating Segments - Active Partner Companies by Segment (Detail)	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Healthcare [Member] | AdvantEdge Healthcare Solutions, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	40.10%	40.10%		40.10%
Healthcare [Member] | Aventura [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	19.90%
Healthcare [Member] | Good Start Genetics, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.60%	29.90%		30.00%
Healthcare [Member] | InfoBionic [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	38.50%	27.80%
Healthcare [Member] | Medivo, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	34.50%	34.50%		34.50%
Healthcare [Member] | meQuilibrium [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.50%
Healthcare [Member] | NovaSom, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.70%	31.70%		30.30%
Healthcare [Member] | Propeller [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.60%	24.60%
Healthcare [Member] | Putney, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	28.20%	28.30%		27.60%
Healthcare [Member] | Syapse, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.40%	27.00%
Healthcare [Member] | Trice [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	27.70%	31.90%
Healthcare [Member] | Zipnosis [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	26.30%
Technology [Member] | Appfirst [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	34.20%	34.30%		34.30%
Technology [Member] | Apprenda, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.50%	21.60%		22.00%
Technology [Member] | Beyond.com, Inc [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	38.20%	38.20%		38.20%
Technology [Member] | Bridgevine, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under cost method, percentage	17.20%	17.20%	[1]	22.70%
Technology [Member] | Cask Data [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	34.20%
Technology [Member] | CloudMine [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	30.10%
Technology [Member] | Clutch [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	39.30%	29.60%		24.00%
Technology [Member] | Full Measure [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	25.40%
Technology [Member] | Hoopla Software, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	25.60%	25.60%		25.30%
Technology [Member] | Lumesis, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	44.70%	45.70%		44.20%
Technology [Member] | MediaMath, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	20.60%	20.70%		22.50%
Technology [Member] | Pneuron [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	35.40%	27.60%		27.60%
Technology [Member] | QuanticMind, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	23.60%
Technology [Member] | Sonobi [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	22.60%
Technology [Member] | Spongecell, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	23.00%	23.00%		23.00%
Technology [Member] | Transactis [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.50%	24.80%
Technology [Member] | WebLinc [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.20%	29.20%

[1] (1) In the second quarter of 2014, the Company’s ownership interest in Bridgevine decreased below the threshold at which the Company believes it exercises significant influence. Accordingly, the Company changed its method of accounting for Bridgevine from the equity method to the cost method.