Information About Segments of Business (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information
Premiums Earned, Net		$ 1,376.7	$ 1,263.4
Realized from actual transactions		18.5	12.3
Unrealized from changes in fair value of equity securities		(962.7)	355.6
Consolidated Revenues [Abstract]
Consolidated revenues		701.5	1,868.6
Title, escrow and other fees		120.1	94.6
Total premiums and fees		1,496.8	1,358.1
Total realized and unrealized investment gains (losses)		(944.1)	368.0
Total Operating Revenues		1,645.7	1,500.6
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)		(769.9)	518.5
Total realized and unrealized investment gains (losses)		(944.1)	368.0
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		(165.1)	106.2
Income tax expense (credits) on consolidated net realized investment gains (losses)	[1]	(198.5)	77.4
Realized from actual transactions and impairments		18.5	12.3
Total Company Segments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		1,634.2	1,488.1
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)		161.8	137.1
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		31.6	26.8
General Insurance Group [Member]
Segment Reporting Information
Premiums Earned, Net	[2]	852.8	831.5
Income (loss) before income taxes (credits) and realized investment gains or losses	[2],[3]	110.1	108.3
Consolidated Revenues [Abstract]
Net investment income and other income	[2]	125.1	118.5
Total Operating Revenues	[2]	978.0	950.0
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[2]	20.8	20.8
Interest charges on intercompany financing arrangements		16.4	18.4
Title Insurance Segment [Member]
Segment Reporting Information
Premiums Earned, Net		508.0	412.2
Income (loss) before income taxes (credits) and realized investment gains or losses	[3]	43.3	20.5
Consolidated Revenues [Abstract]
Title, escrow and other fees		120.1	94.6
Total premiums and fees		628.1	506.9
Net investment income and other income		10.9	10.4
Total Operating Revenues		639.1	517.3
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		9.2	4.3
Interest charges on intercompany financing arrangements		0.9	1.5
RFIG Run-off Business [Member]
Segment Reporting Information
Premiums Earned, Net	[2]	12.6	16.2
Income (loss) before income taxes (credits) and realized investment gains or losses	[2]	8.4	8.2
Consolidated Revenues [Abstract]
Net investment income and other income	[2]	4.3	4.5
Total Operating Revenues	[2]	17.0	20.7
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[2]	1.6	1.6
Other sources - net [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	[4]	39.8	44.0
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits)	[4]	12.3	13.2
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[4]	1.6	2.0
Consolidation elimination adjustments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		$ (28.2)	$ (31.5)

[1] Reflects primarily the combination of fully taxable investment gains or losses.

[2] 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.

[3] 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 - $16.4 and $18.4 for the quarters ended March 31, 2020 and 2019, respectively, and Title - $.9 and $1.5 for the quarters ended March 31, 2020 and 2019, respectively.

[4] 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.