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, 2016	Dec. 31, 2015
Investments in and Advances to Affiliates [Line Items]
Equity method investments	$ 154,666	$ 151,840
Cost method investments	3,662	6,990
Advances to partner companies	25,142	12,771
Total	183,470	171,601
Partner companies [Member]
Investments in and Advances to Affiliates [Line Items]
Equity method investments	154,219	150,898
Cost method investments	2,112	5,024
Private equity funds [Member]
Investments in and Advances to Affiliates [Line Items]
Equity method investments	447	942
Cost method investments	$ 1,550	$ 1,966