Intangible Assets

3 Months Ended

Mar. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

(4) Intangible Assets

Intangible assets associated with customer relationships are amortized on a straight-line basis over the expected period of benefits of the customer relationships, which ranged from 10 to 20 years at the time the intangible assets were originally recorded. The weighted average amortization period for intangible assets is 14.9 years.

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, 2023
Customer relationships, beginning of period	$	1,844.8	$	(923.6)	$	921.2
Amortization expense	—		(31.9)		(31.9)

Customer relationships, end of period	$	1,844.8	$	(955.5)	$	889.3

Amortization expense was $31.9 million and $32.8 million for the three months ended March 31, 2023 and 2022, respectively.

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


2023 (remaining)	$	95.7
2024	127.6
2025	110.2
2026	106.3
2027	106.3
Thereafter	343.2

Total	$	889.3