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Non-controlling Interests (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Total non-controlling interests	$ 110.0	$ (88.1)
Total Non-Controlling Excluding Reciprocals
Noncontrolling Interest [Line Items]
Total non-controlling interests	$ 242.9	$ 35.2
HG Global
Noncontrolling Interest [Line Items]
Noncontrolling equity percentage	3.10%	3.10%
Total non-controlling interests	$ 11.6	$ 13.5
Ark
Noncontrolling Interest [Line Items]
Noncontrolling equity percentage	28.00%	0.00%
Total non-controlling interests	$ 211.0	$ 0.0
Specialty Insurance Distribution (NSM)
Noncontrolling Interest [Line Items]
Noncontrolling equity percentage	3.40%	3.40%
Total non-controlling interests	$ 16.0	$ 17.0
Kudu
Noncontrolling Interest [Line Items]
Noncontrolling equity percentage	0.70%	0.70%
Total non-controlling interests	$ 2.3	$ 2.3
Other
Noncontrolling Interest [Line Items]
Total non-controlling interests	$ 2.0	$ 2.4
BAM
Noncontrolling Interest [Line Items]
Noncontrolling equity percentage	100.00%	100.00%
Total non-controlling interests	$ (132.9)	$ (123.3)

X

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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