Intangible Assets and Goodwill - Summary of Changes in Intangible Assets (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
Jan. 19, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Amortization		$ (0.3)	$ (1.3)	$ (1.2)	$ (3.3)
Goodwill [Roll Forward]
Goodwill, Beginning of the period		3.9	26.0	3.9	24.2
Goodwill, Additions		0.0	0.0	0.0	1.8
Goodwill, End of the period		3.9	26.0	3.9	26.0
Intangible assets and goodwill, Beginning of the period		27.0	79.4	27.9	79.6
Intangible Assets and Goodwill, Acquired		0.0	0.0	0.0	1.8
Intangible assets and goodwill, End of the period		26.7	78.1	26.7	78.1
Trademark
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		2.7	6.3	2.9	6.6
Intangible Assets, Additions		0.0	0.0	0.0	0.0
Amortization		0.0	(0.3)	(0.2)	(0.6)
Intangible Assets, End of the period	$ 4.0	2.7	6.0	2.7	6.0
Insurance Licenses
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		16.7	16.7	16.7	16.7
Intangible Assets, Additions		0.0	0.0	0.0	0.0
Amortization		0.0	0.0	0.0	0.0
Intangible Assets, End of the period		16.7	16.7	16.7	16.7
Agency Relationships
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		2.0	25.1	2.3	26.2
Intangible Assets, Additions		0.0	0.0	0.0	0.0
Amortization		(0.1)	(0.5)	(0.4)	(1.6)
Intangible Assets, End of the period	25.0	1.9	24.6	1.9	24.6
Non-compete Agreements
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		0.5	3.0	0.7	3.3
Intangible Assets, Additions	2.9	0.0	0.0	0.0	0.0
Amortization		(0.1)	(0.3)	(0.3)	(0.6)
Intangible Assets, End of the period		0.4	2.7	0.4	2.7
Consulting Relationships
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		0.0	0.8	0.0	0.9
Intangible Assets, Additions		0.0	0.0	0.0	0.0
Amortization		0.0	(0.1)	0.0	(0.2)
Intangible Assets, End of the period	$ 1.0	0.0	0.7	0.0	0.7
Contractual Rights
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		1.2	1.5	1.4	1.7
Intangible Assets, Additions		0.0	0.0	0.0	0.0
Amortization		(0.1)	(0.1)	(0.3)	(0.3)
Intangible Assets, End of the period		$ 1.1	$ 1.4	$ 1.1	$ 1.4

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Indefinite-lived and Finite-lived Intangible Assets Acquired

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Intangible Assets and Goodwill, Acquired

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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Carrying amount of finite-lived intangible assets, indefinite-lived intangible assets and goodwill. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Intangible assets are assets, not including financial assets, lacking physical substance.

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