Investment Securities (Net Realized and Unrealized Investment Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Net realized investment gains (losses), pre-tax	$ 25.7	$ (5.1)
Net unrealized investment gains (losses), pre-tax (1)	219.9	(48.6)
Net realized and unrealized investment gains (losses), pre-tax	245.6	(53.7)
Income tax (expense) benefit attributable to net realized and unrealized investment gains (losses)	(52.2)	5.7
Net realized and unrealized investment gains (losses), after-tax	193.4	$ (48.0)
MediaAlpha
Unrealized investment gain	$ 114.7

The sum of the realized and unrealized net gain (loss) on trading securities during the period.

No definition available.

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Represents the equity in unrealized gains or losses from investments in unconsolidated affiliates.

No definition available.

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Net Realized and Unrealized Gain (Loss) on Trading Securities, Net of Tax

No definition available.

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The aggregate of the change in unrealized holding gain (loss) and foreign currency gain (loss) included in earnings during the reporting period.

No definition available.

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Tax on net realized and unrealized gains (loss), trading securities

No definition available.

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Trading Securities, Realized Gain (Loss), Total

No definition available.

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Balance Type:	credit
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