Summary of Significant Accounting Policies Unearned Premiums (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Unearned premiums	$ 2,224.7	$ 2,104.9
General Insurance Group [Member]
Unearned premiums	2,223.4	2,101.8
RFIG Run-off Business [Member]
Unearned premiums	$ 1.3	$ 3.0

Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(13)(a)(2))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Name:	us-gaap_UnearnedPremiums
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant