Information About Segments of Business (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information
Realized from actual transactions		$ 12.3	$ 15.5
Unrealized from changes in fair value of equity securities		355.6	(152.0)
Consolidated Revenues [Abstract]
Consolidated revenues		1,868.6	1,330.4
Net premiums earned		1,263.4	1,231.0
Title, escrow and other fees		94.6	99.3
Total premiums and fees		1,358.1	1,330.4
Total realized and unrealized investment gains (losses)		368.0	(136.4)
Total operating revenues		1,500.6	1,466.8
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		518.5	(6.0)
Total realized and unrealized investment gains (losses)		368.0	(136.4)
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		106.2	(10.1)
Income tax expense (credits) on consolidated net realized investment gains (losses)	[1]	77.4	(28.7)
Total Company Segments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		1,488.1	1,455.2
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		137.1	123.8
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		26.8	20.1
General Insurance Group [Member]
Consolidated Revenues [Abstract]
Net premiums earned		831.5	791.2
Net investment income and other income		118.5	113.5
Segment pretax operating income (loss)	[2]	108.3	83.3
Total operating revenues		950.0	904.8
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		20.8	11.5
Interest charges on intercompany financing arrangements		18.4	15.4
Title Insurance Segment [Member]
Consolidated Revenues [Abstract]
Net premiums earned		412.2	414.5
Title, escrow and other fees		94.6	99.3
Total premiums and fees		506.9	513.8
Net investment income and other income		10.4	9.7
Segment pretax operating income (loss)	[2]	20.5	29.5
Total operating revenues		517.3	523.6
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		4.3	6.3
Interest charges on intercompany financing arrangements		1.5	1.4
RFIG Run-off Business [Member]
Consolidated Revenues [Abstract]
Net premiums earned		16.2	21.3
Net investment income and other income		4.5	5.3
Segment pretax operating income (loss)		8.2	10.9
Total operating revenues		20.7	26.7
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)		1.6	2.2
Other sources - net [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	[3]	44.0	41.4
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	[3]	13.2	6.5
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	[3]	2.0	(1.5)
Consolidation elimination adjustments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues		$ (31.5)	$ (29.7)

[1] Reflects primarily the combination of fully taxable investment gains or losses and judgments about the recoverability of deferred tax assets.

[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 - $18.4 and $15.4 for the quarters ended March 31, 2019 and 2018, respectively, and Title - $1.5 and $1.4 for the quarters ended March 31, 2019 and 2018, 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.