Information About Segments of Business (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information
Premiums Earned, Net		$ 1,353.1	$ 1,329.6	$ 2,729.8	$ 2,593.0
Unrealized from changes in fair value of equity securities		354.0	26.3	(608.7)	382.0
Consolidated Revenues [Abstract]
Consolidated revenues		1,970.6	1,644.7	2,672.2	3,513.4
Title, escrow and other fees		129.9	130.9	250.0	225.6
Total premiums and fees		1,483.1	1,460.5	2,979.9	2,818.6
Total realized and unrealized investment gains (losses)		346.7	36.9	(597.4)	405.0
Total Operating Revenues		1,623.9	1,607.7	3,269.6	3,108.3
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)		499.1	205.4	(270.8)	723.9
Total realized and unrealized investment gains (losses)		346.7	36.9	(597.4)	405.0
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		101.4	39.9	(63.7)	146.1
Income tax expense (credits) on consolidated net realized investment gains (losses)		72.8	7.7	(125.7)	85.1
Realized from actual transactions and impairments		(7.3)	10.5	11.2	22.9
Total Company Segments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		1,614.3	1,594.8	3,248.5	3,082.9
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)		145.6	155.2	307.5	292.4
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		28.0	30.4	59.7	57.2
General Insurance Group [Member]
Segment Reporting Information
Premiums Earned, Net	[1]	818.0	850.1	1,670.8	1,681.6
Income (loss) before income taxes (credits) and realized investment gains or losses	[1],[2]	85.2	86.7	195.3	195.0
Consolidated Revenues [Abstract]
Net investment income and other income	[1]	119.6	122.8	244.8	241.3
Total Operating Revenues	[1]	937.6	972.9	1,915.6	1,923.0
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[1]	15.5	16.1	36.4	36.9
Interest charges on intercompany financing arrangements		15.7	17.9	32.1	36.4
Title Insurance Segment [Member]
Segment Reporting Information
Premiums Earned, Net		520.4	460.6	1,028.5	872.9
Income (loss) before income taxes (credits) and realized investment gains or losses	[2]	65.4	60.2	108.7	80.8
Consolidated Revenues [Abstract]
Title, escrow and other fees		129.9	130.9	250.0	225.6
Total premiums and fees		650.4	591.6	1,278.6	1,098.5
Net investment income and other income		10.5	10.4	21.5	20.8
Total Operating Revenues		661.0	602.0	1,300.1	1,119.4
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		13.6	12.6	22.8	17.0
Interest charges on intercompany financing arrangements		0.6	1.5	1.6	3.0
RFIG Run-off Business [Member]
Segment Reporting Information
Premiums Earned, Net	[1]	11.6	15.3	24.3	31.5
Income (loss) before income taxes (credits) and realized investment gains or losses	[1]	(4.9)	8.2	3.4	16.5
Consolidated Revenues [Abstract]
Net investment income and other income	[1]	3.9	4.3	8.3	8.9
Total Operating Revenues	[1]	15.6	19.7	32.6	40.5
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[1]	(1.1)	1.6	0.4	3.2
Other sources - net [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	[3]	36.3	44.1	76.1	88.1
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)	[3]	6.7	13.2	19.0	26.4
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[3]	0.5	1.6	2.2	3.7
Consolidation elimination adjustments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		$ (26.7)	$ (31.1)	$ (55.0)	$ (62.7)

[1] Results for the Consumer Credit Indemnity ("CCI") run-off business are expected to be immaterial in the remaining run-off periods. Effective July 1, 2019 these results have been reclassified to the General Insurance segment for all future periods. Previously these results were reflected as part of the RFIG Run-off Business.

[2] Segment pretax operating income (loss) is reported net of interest charges on intercompany financing arrangements with Old Republic's holding company parent for the following segments: General - $15.7 and $32.1 compared to $17.9 and $36.4 for the quarters and six months ended June 30, 2020 and 2019, respectively, and Title - $.6 and $1.6 compared to $1.5 and $3.0 for the quarters and six months ended June 30, 2020 and 2019, respectively.

[3] 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.