Total Capital Commitments, Unfunded Capital Commitments, and Our Ownership in Each Fund (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Venture Capital and Private Equity Fund Investments [Line Items]
Unfunded Commitments	$ 5,842
Strategic Investors Fund, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Unfunded Commitments	1,338
Capital Preferred Return Fund, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Unfunded Commitments	1,952
Growth Partners, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Unfunded Commitments	2,552
Parent Company
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	464,655
Unfunded Commitments	16,142
Parent Company | CP I, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	6,000
Unfunded Commitments	$ 270
Ownership percentage of each Fund	10.70%
Parent Company | CP II, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 1,200
Unfunded Commitments	$ 162
Ownership percentage of each Fund	5.10%
Parent Company | Shanghai Yangpu Venture Capital Fund (LP)
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 891
Unfunded Commitments	$ 0
Ownership percentage of each Fund	6.80%
Parent Company | Strategic Investors Fund, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 15,300
Unfunded Commitments	$ 688
Ownership percentage of each Fund	12.60%
Parent Company | Strategic Investors Fund II, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 15,000
Unfunded Commitments	$ 1,050
Ownership percentage of each Fund	8.60%
Parent Company | Strategic Investors Fund III, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 15,000
Unfunded Commitments	$ 1,275
Ownership percentage of each Fund	5.90%
Parent Company | Strategic Investors Fund IV, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 12,239
Unfunded Commitments	$ 2,325
Ownership percentage of each Fund	5.00%
Parent Company | Strategic Investors Fund V Funds
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 515
Unfunded Commitments	131
Parent Company | Capital Preferred Return Fund, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	12,688
Unfunded Commitments	$ 0
Ownership percentage of each Fund	20.00%
Parent Company | Growth Partners, L.P.
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 24,670
Unfunded Commitments	$ 1,340
Ownership percentage of each Fund	33.00%
Parent Company | Debt Funds (Equity Method Accounting)
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	$ 58,493
Unfunded Commitments	0
Parent Company | Other Fund Investments
Venture Capital and Private Equity Fund Investments [Line Items]
Capital Commitments	302,659
Unfunded Commitments	$ 8,901