Information About Segments of Business Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item
Assets		$ 21,650.3	$ 21,076.3
General Insurance Group [Member]
Segment Reporting, Asset Reconciling Item
Assets		18,533.8	17,870.0
Title Insurance Segment [Member]
Segment Reporting, Asset Reconciling Item
Assets		1,684.5	1,695.0
RFIG Run-off Business [Member]
Segment Reporting, Asset Reconciling Item
Assets		556.6	615.1
Total Company Segments [Member]
Segment Reporting, Asset Reconciling Item
Assets		20,775.0	20,180.2
All Other Segments [Member]
Segment Reporting, Asset Reconciling Item
Assets	[1]	1,083.4	1,095.4
Intersegment Elimination [Member]
Segment Reporting, Asset Reconciling Item
Assets		$ (208.1)	$ (199.3)

[1] Includes amounts for a small life and accident insurance business as well as those of the parent holding company and its internal corporate services subsidiaries.