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Ownership Interests in and Advances to Partner Companies and Funds - Narrative (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended						5 Months Ended	12 Months Ended
	Jan. 31, 2016	Jul. 31, 2015	Apr. 30, 2015	Feb. 28, 2014	Jan. 31, 2014	Dec. 31, 2013	Jul. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Proceeds from sale of business								$ 25,058	$ 82,822	$ 38,974
Adjusted carrying value of capital								151,840	135,989
Equity method investment assets exceed carrying value of investment								105,600
Goodwill [Member]
Investment [Line Items]
Equity method investment allocation of excess fair value								78,800
Intangible Assets [Member]
Investment [Line Items]
Equity method investment allocation of excess fair value								26,800
Thing Worx Inc [Member]
Investment [Line Items]
Proceeds from sale of business		$ 3,300				$ 36,400
Gain on sale of business								3,300		32,700
Proceeds from milestone payments								3,200
Alverix Inc [Member]
Investment [Line Items]
Proceeds from sale of business		1,700			$ 15,700				15,700
Gain on sale of business								1,700	15,700
Crescendo [Member]
Investment [Line Items]
Proceeds from sale of business				$ 38,400			$ 2,900		38,400
Gain on sale of business								2,900
Cost-method Investments, realized gains									27,400
Quantia [Member]
Investment [Line Items]
Proceeds from sale of business		7,800
Amount held in escrow		$ 1,200					$ 1,200
Asset impairment charges								2,900
DriveFactor Inc. [Member]
Investment [Line Items]
Proceeds from sale of business			$ 9,100
Gain on sale of business								6,100
Amount held in escrow			1,100
InfoBionic [Member]
Investment [Line Items]
Asset impairment charges								3,200
Dabo [Member]
Investment [Line Items]
Asset impairment charges								2,300
Sotera [Member]
Investment [Line Items]
Proceeds from sale of business			$ 4,200
Cost-method Investments, realized gains									1,500
Nupathe [Member]
Investment [Line Items]
Proceeds from sale of business				23,100
Gain on sale of business									$ 3,000
Proceeds from milestone payments				$ 24,200
Proceeds from divestiture of businesses and interests in affiliates (in dollars per share)				$ 3.65
Proceeds from milestone payments (in dollars per share)				$ 3.15
Appfirst [Member]
Investment [Line Items]
Asset impairment charges								3,600
Adjusted carrying value of capital								$ 3,000
PixelOptics, Inc. [Member]
Investment [Line Items]
Asset impairment charges										$ 11,200
Subsequent Event [Member] \| Thing Worx Inc [Member]
Investment [Line Items]
Proceeds from sale of business	$ 4,100
Gain on sale of business	$ 4,100