Other Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Other Intangible Assets

Other Intangible Assets

	December 31, 2018							December 31, 2017
	Weighted Average Remaining Useful Life (Years)	Gross Value		Accumulated Amortization		Net Value		Gross Value		Accumulated Amortization		Net Value
Customer relationships	11.0	$	86.0	$	34.5	$	51.5	$	83.4	$	29.3	$	54.1
Indefinite-lived tradenames	*	24.1		*		24.1		23.7		*		23.7
Technology	16.5	22.9		4.1		18.8		23.6		3.0		20.6
Other	6.6	4.1		3.2		0.9		4.1		3.0		1.1
Total		$	137.1	$	41.8	$	95.3	$	134.8	$	35.3	$	99.5
* Not applicable, as these tradenames have an indefinite life.

Amortization expense of other intangible assets as follows:

	Year Ended December 31,
	2018		2017		2016
Amortization expense	$	6.9	$	6.6	$	6.1

We estimate amortization expense for the five years subsequent to December 31, 2018 as follows:

2019	$	6.2
2020	$	6.1
2021	$	6.1
2022	$	6.1
2023	$	6.1