Fair Value of Financial Instruments - Summary of Estimated Fair Values of Investments and Remaining Unfunded Commitments for Each Major Category of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	$ 1,230,364
Fair Value	1,319,978
Unfunded Commitments	540,099
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	1,040,522
Fair Value	1,040,522
Unfunded Commitments	506,163
Non-marketable securities | Equity method accounting | Other investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	47,706
Fair Value	49,220
Unfunded Commitments	5,836
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	142,136
Fair Value	230,236
Unfunded Commitments	$ 28,100