INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2021

Intangible Assets, Net (Excluding Goodwill) [Abstract]

The following table presents the major classes of the company's intangible assets at December 31, 2021 and 2020:


$ in millions	Gross Book Value	Accumulated Amortization	Net Book Value
December 31, 2021
Management contracts - indefinite-lived	6,968.3	N/A	6,968.3
Management contracts - finite-lived	319.2	(151.4)	167.8
Developed technology	98.1	(68.2)	29.9
Other	109.7	(47.7)	62.0
Total	7,495.3	(267.3)	7,228.0
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

The 2021 and 2020 annual impairment reviews of indefinite-lived intangible assets determined that no impairment existed. No interim impairment test was deemed necessary for 2021. Due to the decline in our assets under management in the three months ended March 31, 2020, management determined that an interim impairment test was necessary for certain of our indefinite-lived management contract assets during 2020. The analysis resulted in no impairment because the fair value of indefinite-lived intangible assets exceeded their carrying value.

Amortization expense was $62.9 million during the year ended December 31, 2021 (December 31, 2020: $62.5 million; December 31, 2019: $52.7 million). Estimated amortization expense for each of the five succeeding fiscal years based upon the company's intangible assets at December 31, 2021 is as follows:


$ in millions Years Ended December 31,			Estimated Amortization Expense
2022			(60.1)
2023			(52.0)
2024			(46.3)
2025			(39.2)
2026			(37.3)