Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of Changes in Carrying Value

The following table represents our change in carrying value of intangible assets for the periods stated (in millions):

	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Year Ended December 31, 2023
Customer relationships, beginning of period	$	1,844.8	$	(923.6)	$	921.2
Amortization expense	—		(127.6)		(127.6)
Customer relationships, end of period	$	1,844.8	$	(1,051.2)	$	793.6
Year Ended December 31, 2022
Customer relationships, beginning of period	$	1,844.8	$	(795.1)	$	1,049.7
Amortization expense	—		(128.5)		(128.5)
Customer relationships, end of period	$	1,844.8	$	(923.6)	$	921.2
Year Ended December 31, 2021
Customer relationships, beginning of period	$	1,794.2	$	(668.8)	$	1,125.4
Customer relationships obtained from acquisition of business	50.6		—		50.6
Amortization expense	—		(126.3)		(126.3)
Customer relationships, end of period	$	1,844.8	$	(795.1)	$	1,049.7

Schedule of Amortization Expense

The following table summarizes our estimated aggregate amortization expense for the next five years and thereafter (in millions):

2024	$	127.6
2025	110.2
2026	106.3
2027	106.3
2028	106.3
Thereafter	236.9
Total	$	793.6