Ownership Interests in and Advances to Partner Companies and Funds - Unaudited Summarized Balance sheets for PixelOptics (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Current assets	$ 312,621	$ 221,001
Non-current assets	90,469	90,042
Total assets	403,090	311,043
Current liabilities	163,016	153,398
Non-current liabilities	80,050	75,324
Shareholders’ equity	160,024	82,321
Total liabilities and shareholders’ equity	403,090	311,043
PixelOptics, Inc. [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Current assets			285	323
Non-current assets			4,588	5,259
Total assets			4,873	5,582
Current liabilities			56,721	34,184
Non-current liabilities			1,818	10,228
Shareholders’ equity			(53,666)	(38,830)
Total liabilities and shareholders’ equity			$ 4,873	$ 5,582