Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Schedule of Finite-Lived Intangible Assets by Major Class

The following table presents the major classes of the company's intangible assets at December 31, 2020 and 2019:

$ in millions	Gross Book Value	Accumulated Amortization	Net Book Value
December 31, 2020
Management contracts - indefinite-lived	6,982.7	N/A	6,982.7
Management contracts - finite-lived	319.9	(118.7)	201.2
Developed technology	99.2	(50.9)	48.3
Other	110.8	(37.4)	73.4
Total	7,512.6	(207.0)	7,305.6
December 31, 2019
Management contracts - indefinite-lived	6,969.1	N/A	6,969.1
Management contracts - finite-lived	319.3	(84.5)	234.8
Developed technology	98.6	(31.7)	66.9
Other	112.2	(24.7)	87.5
Total	7,499.2	(140.9)	7,358.3

Schedule Of Future Amortization Expense Of Intangible Assets

Estimated amortization expense for each of the five succeeding fiscal years based upon the company's intangible assets at December 31, 2020 is as follows:

$ in millions Years Ended December 31,	Estimated Amortization Expense
2021	(62.8)
2022	(60.3)
2023	(52.0)
2024	(46.4)
2025	(39.2)