Reinsurance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reinsurance Disclosures [Abstract]
Percentage of ceded earned premiums to gross earned premiums	16.00%	18.00%	16.00%	18.00%
Percentage of assumed earned premiums to net earned premiums	30.00%	31.00%	31.00%	31.00%
Reinsurance recoverables	$ 109.0	$ 75.5	$ 208.6	$ 206.1

Percentage of ceded premiums earned by the entity to gross premiums earned.

No definition available.

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- Definition

Percentage of assumed premiums earned by the entity to net premiums earned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17)
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387

+ Details

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