Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of Changes in Carrying Value

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

	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Three Months Ended March 31, 2021
Customer relationships, beginning of period	$	1,794.2	$	(668.8)	$	1,125.4
Amortization expense	—		(30.9)		(30.9)
Customer relationships, end of period	$	1,794.2	$	(699.7)	$	1,094.5

Schedule of Amortization Expense

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

2021 (remaining)	$	92.5
2022	123.4
2023	123.4
2024	123.4
2025	106.1
Thereafter	525.7
Total	$	1,094.5