Intangible Assets

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

18. Intangible Assets

At December 31, 2023	Cost		Accumulated amortization		Net book value
Trade names and trademarks	$	221.9	$	(29.7)	$	192.2
Customer relationships	2,553.1		(225.0)		2,328.1
Software and technology assets	670.4		(285.5)		384.9
Software under development	8.9		—		8.9
Backlog	1.1		(1.1)		—
	$	3,455.4	$	(541.3)	$	2,914.1

At December 31, 2022	Cost		Accumulated amortization		Net book value
Trade names and trademarks	$	54.0	$	(2.9)	$	51.1
Customer relationships	245.4		(85.6)		159.8
Software and technology assets	289.1		(182.3)		106.8
Software under development	4.5		—		4.5
Backlog	1.1		(0.6)		0.5
	$	594.1	$	(271.4)	$	322.7

At December 31, 2023, a net carrying amount of $59.0 million (December 31, 2022: $54.5 million) included in intangible assets was not subject to amortization, $50.1 million of which relates to certain trade names and trademarks and the remainder relates to software under development . During the year ended December 31, 2023, the cost of additions was reduced by $1.4 million for recognition of tax credits (2022: $1.1 million; 2021: $2.2 million).

During the year ended December 31, 2023, interest of $1.6 million (2022: $0.4 million; 2021: $0.3 million) was capitalized to the cost of software under development.

At December 31, 2023, estimated annual amortization expense for the next five years ended December 31 are as follows:

2024	$	321.5
2025	304.2
2026	290.8
2027	228.1
2028	185.0
	$	1,329.6