Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

For the three months ended March 31, 2018, there were no changes to the carrying amounts of goodwill.

	Permian		North Texas		Oklahoma		Louisiana			Corporate			Totals
Three Months Ended March 31, 2019
Balance, beginning of period	$	—	$	—	$	190.3	$	—		$	1,119.9		$	1,310.2
Goodwill allocation	184.6		125.7		623.1		186.5			(1,119.9		)	—
Impairment	—		—		—		(186.5		)	—			(186.5		)
Balance, end of period	$	184.6	$	125.7	$	813.4	$	—		$	—		$	1,123.7

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, 2019
Customer relationships, beginning of period	$	1,795.8	$	(422.2	)	$	1,373.6
Amortization expense	—		(30.9		)	(30.9		)
Customer relationships, end of period	$	1,795.8	$	(453.1	)	$	1,342.7

Schedule of Amortization Expense

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

2019 (remaining)	$	92.8
2020	123.7
2021	123.7
2022	123.7
2023	123.6
Thereafter	755.2
Total	$	1,342.7