Fair Value of Financial Instruments - Summary of Estimated Fair Values of Investments and Remaining Unfunded Commitments for Each Major Category of Investments (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	$ 390,774
Fair Value	507,306
Unfunded Commitments	22,388
Non-marketable securities | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	145,649
Fair Value	145,649
Unfunded Commitments	6,610
Non-marketable securities | Equity method accounting | Venture capital and private equity fund investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	83,555
Fair Value	83,555
Unfunded Commitments	4,954
Non-marketable securities | Equity method accounting | Debt funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	21,809
Fair Value	23,066
Unfunded Commitments	0
Non-marketable securities | Equity method accounting | Other investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	22,352
Fair Value	22,352
Unfunded Commitments	886
Non-marketable securities | Cost method accounting | Venture capital and private equity fund investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	117,409
Fair Value	232,684
Unfunded Commitments	$ 9,938