Acquisitions of Ownership Interests in Partner Companies and Funds (Detail) - USD ($) $ in Thousands	1 Months Ended							2 Months Ended		4 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Jul. 31, 2015	Jun. 30, 2015	May. 31, 2015	Apr. 30, 2015	Mar. 31, 2015	Feb. 28, 2015	Jan. 31, 2015	Apr. 30, 2015	Feb. 28, 2015	May. 31, 2015	Apr. 30, 2015	Jun. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments													$ 52,181	$ 54,956
Apprenda [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	$ 10,000											$ 12,100
InfoBionic [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	$ 1,500											8,000
Quantia [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments															$ 12,500
Convertible bridge loan												2,800
AppFirst, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments															8,600
Convertible bridge loan												$ 2,000
InsideVault [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments		$ 7,000
Ownership interest under equity method, percentage		24.50%										24.50%
Pneuron [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments			$ 3,500								$ 5,000
Clutch [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 7,500			$ 4,800
Sonobi [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments			$ 5,400
Ownership interest under equity method, percentage			22.60%							22.60%
Advantedge [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments									$ 15,300
Convertible bridge loan								$ 1,000
meQuilibrium [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments				$ 6,500
Ownership interest under equity method, percentage				31.50%				31.50%			31.50%
Spongecell [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments									10,000
Convertible bridge loan					$ 4,000
Dabo [Member]
Schedule of Equity Method Investments [Line Items]
Convertible bridge loan					$ 300
Payments to acquire cost method investments									$ 2,000
CloudMine [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments						$ 2,900
Ownership interest under equity method, percentage						30.10%			30.10%
Aventura [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 6,000
Ownership interest under equity method, percentage							19.90%
Full Measure [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 4,000
Ownership interest under equity method, percentage							25.40%
Trice [Member]
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 1,100								$ 5,000