Other Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Other Intangible Assets

 Other Intangible Assets

A summary of our identifiable intangible assets are as follows (in millions):

As of December 31, 2018	Useful Life	Gross		Accumulated Amortization			Net
Intangible Assets subject to amortization:
Supply contract	11.5 years	$	12.2	$	(12.2	)	$	—
Third-party fuel supply agreement	10 years	49.0		(7.4		)	41.6
Capacity contract	8 years	9.3		(9.3		)	—
Fuel trade name	5 years	4.0		(1.2		)	2.8
Below market leases	13 - 15 years	8.3		(0.3		)	8.0
Intangible assets not subject to amortization:
Rights-of-way	Indefinite	30.0					30.0
Line space history	Indefinite	11.3					11.3
Liquor licenses	Indefinite	8.5					8.5
Refinery permits	Indefinite	2.2					2.2
Total		$	134.8	$	(30.4	)	$	104.4

As of December 31, 2017	Useful Life	Gross		Accumulated Amortization			Net
Intangible Assets subject to amortization:
Supply contract	11.5 years	$	12.2	$	(12.2	)	$	—
Third-party fuel supply agreement	10 years	49.0		(2.4		)	46.6
Capacity contract	8 years	9.3		(9.2		)	0.1
Fuel trade name	5 years	4.0		(0.4		)	3.6
Below market leases	13 - 15 years	0.6		(0.1		)	0.5
Intangible assets not subject to amortization:
Rights-of-way	Indefinite	30.1					30.1
Line space history	Indefinite	9.6					9.6
Liquor licenses	Indefinite	8.5					8.5
Refinery permits	Indefinite	2.1					2.1
Total		$	125.4	$	(24.3	)	$	101.1

Amortization of intangible assets was $6.1 million, $3.8 million, and $1.3 million during the years ended December 31, 2018, 2017 and 2016, respectively, and is included in depreciation and amortization on the accompanying consolidated statements of income, with the exception of an immaterial amount related to below market leases.

Amortization expense for the next five years is estimated to be as follows:

2019	$	5.9
2020	5.9
2021	5.9
2022	5.5
2023	5.1