Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Net Carrying Amount of Other Intangible Assets

The following table is a summary of the net carrying amount of other intangible assets as of December 31:



(millions)	2018		2017
Intangible assets subject to amortization	$	282.2	$	354.2
Indefinite-lived intangible assets¹	12.4		12.4
Total	$	294.6	$	366.6

¹Indefinite-lived intangible assets are comprised of state insurance and agent licenses. State insurance licenses were previously subject to amortization under superseded accounting guidance and have $0.6 million of accumulated amortization for both years presented.

Intangible Assets Subject to Amortization

Intangible assets subject to amortization for the years ended December 31, consisted of the following:



(millions)	2018						2017
Category	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Policies in force	$	256.2	$	137.3	$	118.9	$	256.2	$	100.7	$	155.5
Agency relationships	159.2		42.6		116.6		159.2		31.3		127.9
Software rights	79.1		40.1		39.0		79.1		29.4		49.7
Trade name	34.8		27.1		7.7		34.8		13.7		21.1
Total	$	529.3	$	247.1	$	282.2	$	529.3	$	175.1	$	354.2

Amortization on Intangible Assets

The estimated aggregate amortization on these intangible assets for each of the next five years as of December 31, 2018, is as follows:



(millions)
Year	Amortization Expense
2019	$	66.4
2020	56.9
2021	56.6
2022	29.2
2023	13.5