Business Combinations, Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

Goodwill activity was as follows for each period presented (in millions of dollars):

	December 31, 2018			Add: Impairment of IMT Goodwill			December 31, 2019
Goodwill	$	62.4		$	—		$	62.4
Accumulated impairment loss	(18.4		)	(25.2		)	(43.6		)
Carrying value	$	44.0		$	(25.2	)	$	18.8

	December 31, 2017			Add: Goodwill from IMT Acquisition		December 31, 2018
Goodwill	$	37.2		$	25.2	$	62.4
Accumulated impairment loss	(18.4		)	—		(18.4		)
Carrying value	$	18.8		$	25.2	$	44.0

Schedule of Finite-Lived Intangible Assets [Table Text Block]

Intangible Assets. Information regarding our intangible assets consisted of the following as of the periods presented (in millions of dollars, except amortization periods):

	Weighted-Average Amortization Period (in years)	Gross Amount		Accumulated Amortization			Intangible Assets, Net
December 31, 2019
Customer relationships	24	$	36.1	$	(12.7	)	$	23.4
Trade name	10	2.4		(0.3		)	2.1
Non-compete agreement	5	5.4		(1.3		)	4.1
Total		$	43.9	$	(14.3	)	$	29.6
December 31, 2018
Customer relationships	24	$	36.1	$	(11.1	)	$	25.0
Trade name	10	2.4		(0.1		)	2.3
Non-compete agreement	5	5.4		(0.3		)	5.1
Total		$	43.9	$	(11.5	)	$	32.4

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Amortization expense relating to definite-lived intangible assets was $2.8 million for 2019, $1.8 million for 2018, and $1.4 million for 2017. The expected amortization of intangible assets for each of the next five calendar years is as follows (in millions of dollars):

2020	$	2.8
2021	2.8
2022	2.8
2023	2.6
2024	1.8
Thereafter	16.8
Total	$	29.6