Information About Segments of Business Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item
Assets		$ 20,352.2	$ 21,076.3
General Insurance Group [Member]
Segment Reporting, Asset Reconciling Item
Assets		17,444.8	17,870.0
Title Insurance Segment [Member]
Segment Reporting, Asset Reconciling Item
Assets		1,607.9	1,695.0
RFIG Run-off Business [Member]
Segment Reporting, Asset Reconciling Item
Assets		534.7	615.1
Total Company Segments [Member]
Segment Reporting, Asset Reconciling Item
Assets		19,587.5	20,180.2
All Other Segments [Member]
Segment Reporting, Asset Reconciling Item
Assets	[1]	918.8	1,095.4
Intersegment Elimination [Member]
Segment Reporting, Asset Reconciling Item
Assets		$ (154.0)	$ (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.