Revenue (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Revenue, Major Customer [Line Items]
Total operating revenues	$ 1,721,400,000	$ 1,419,000,000.0	$ 3,381,100,000	$ 3,017,900,000
Deferred carried interest liabilities	59,800,000		59,800,000		$ 58,000,000.0	$ 45,800,000
Performance revenue recognized			0	0
Bermuda
Revenue, Major Customer [Line Items]
Total operating revenues			0	0
Americas
Revenue, Major Customer [Line Items]
Total operating revenues	1,282,300,000	1,057,200,000	2,513,000,000.0	2,237,900,000
UK
Revenue, Major Customer [Line Items]
Total operating revenues	164,700,000	146,000,000.0	328,300,000	316,800,000
EMEA ex UK (Europe, Middle East and Africa)
Revenue, Major Customer [Line Items]
Total operating revenues	184,200,000	145,700,000	360,500,000	310,100,000
Asia Pacific
Revenue, Major Customer [Line Items]
Total operating revenues	$ 90,200,000	$ 70,100,000	$ 179,300,000	$ 153,100,000