Total Capital Commitments, Unfunded Capital Commitments, and Our Ownership in Each Fund (Footnote Information) (Detail) - Venture capital and private equity fund investments - Investment	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
CP II, L.P. | Fair value accounting | Direct ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	1.30%
CP II, L.P. | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	3.80%
Other private equity fund | Fair value accounting
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	58.20%	58.20%
Other private equity fund | Fair value accounting | Direct ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	41.50%
Other Fund Investments
Venture Capital and Private Equity Fund Investments [Line Items]
Number of other funds with investment commitments	258
Upper Limit | Other Fund Investments
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	5.00%
Growth Partners, L.P. | Other private equity fund | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	12.60%
Capital Preferred Return Fund, L.P. | Other private equity fund | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Company Direct and Indirect Ownership in Limited Partnership	4.10%