Investments - Partnership's Equity Method Investees, Summarized Statement of Income Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Investment income	$ 1,015.5	$ 1,836.5	$ 1,933.6
Expenses	1,263.9	1,392.5	1,069.5
Net investment income (loss)	(248.4)	444.0	864.1
Net realized and unrealized gain (loss)	1,460.9	11,245.9	10,310.4
Net income (loss)	1,212.5	11,689.9	11,174.5
Corporate Private Equity
Schedule of Investments [Line Items]
Investment income	380.7	528.3	699.7
Expenses	613.8	665.6	495.9
Net investment income (loss)	(233.1)	(137.3)	203.8
Net realized and unrealized gain (loss)	4,831.6	8,387.9	9,795.5
Net income (loss)	4,598.5	8,250.6	9,999.3
Global Market Strategies
Schedule of Investments [Line Items]
Investment income	193.6	193.5	199.3
Expenses	45.7	48.7	65.0
Net investment income (loss)	147.9	144.8	134.3
Net realized and unrealized gain (loss)	(323.1)	247.0	305.2
Net income (loss)	(175.2)	391.8	439.5
Real Assets
Schedule of Investments [Line Items]
Investment income	441.2	1,114.7	1,034.6
Expenses	604.4	678.2	508.6
Net investment income (loss)	(163.2)	436.5	526.0
Net realized and unrealized gain (loss)	(3,047.6)	2,611.0	209.7
Net income (loss)	$ (3,210.8)	$ 3,047.5	$ 735.7