Ownership Interests in and Advances to Partner Companies and Funds - Summary of the carrying value of the Company's ownership interests in and advances to partner companies and private equity funds (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments in and Advances to Affiliates [Line Items]
Equity method investments	$ 34,542	$ 64,489
Cost method investments	27,484	15,771
Advances to companies	15,103	15,325
Total	77,129	95,585
Partner companies [Member]
Investments in and Advances to Affiliates [Line Items]
Equity method investments	34,271	64,097
Cost method investments	27,031	15,260
Private equity funds [Member]
Investments in and Advances to Affiliates [Line Items]
Equity method investments	271	392
Cost method investments	$ 453	$ 511