Investments - Investments, at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	$ 2,236,648	$ 2,012,027
Investment Cost	1,590,140	1,588,961
Percentage of Net Assets of Consolidated Investments Funds	100.10%	100.00%
Other Investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	907	839
Investment Cost	4,081	4,159
AAA
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	2,147,415	1,942,051
Investment Cost	1,494,358	1,494,358
Percentage of Net Assets of Consolidated Investments Funds	98.70%	98.50%
Apollo Senior Loan Fund
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	29,909	29,603
Investment Cost	29,612	29,226
Percentage of Net Assets of Consolidated Investments Funds	1.40%	1.50%
HFA
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	58,417	39,534
Investment Cost	62,089	61,218
Private Equity Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	2,148,322	1,942,890
Private Equity Funds | Other Investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	907	839
Private Equity Funds | AAA
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	2,147,415	1,942,051
Credit
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	88,326	69,137
Credit | Apollo Senior Loan Fund
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	29,909	29,603
Credit | HFA
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments, at fair value	$ 58,417	$ 39,534