Information About Segments of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Dec. 31, 2011
Consolidated Revenues [Abstract]
Net premiums earned	$ 981.4		$ 890.5		$ 1,925.0		$ 1,813.3
Title, escrow and other fees	107.1		87.2		201.1		167.4
Sub-total	1,088.5		977.7		2,126.1		1,980.8
Total operating revenues	1,201.9		1,097.9		2,357.0		2,221.0
Consolidated net realized investment gains (losses)	22.0		(2.9)	[1]	24.9		3.5	[1]
Consolidated revenues	1,223.9		1,094.9	[1]	2,382.0		2,224.5	[1]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Consolidated net realized investment gains (losses)	22.0		(2.9)	[1]	24.9		3.5	[1]
Consolidated income (loss) before income taxes (credits)	(58.3)		(108.3)	[1]	(60.9)		(133.3)	[1]
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	(24.2)		(42.0)	[1]	(27.3)		(54.0)	[1]
Income tax expense (credits) on consolidated net realized investment gains (losses)	7.7	[2]	(1.0)	[1],[2]	8.7	[2]	1.2	[1]
Assets	15,875.2				15,875.2				16,050.4	[1]
Deferred payment obligation	192.3				192.3
General Insurance Group [Member]
Consolidated Revenues [Abstract]
Net premiums earned	564.1		510.5	[1]	1,113.1		1,022.0	[1]
Net investment income and other income	93.7		93.5	[1]	190.6		186.6	[1]
Total operating revenues	657.8		604.0	[1]	1,303.7		1,208.7	[1]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits) and realized investment gains or losses	59.6	[3]	82.0	[1],[3]	140.1	[3]	170.9	[1],[3]
Interest charges on intercompany financing arrangements	6.9		6.0		13.8		11.4
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	16.9		25.1	[1]	42.9		53.5	[1]
Assets	12,510.2				12,510.2				12,311.2	[1]
Deferred policy acquisition costs	11				22
RFIG Run-off Business [Member]
Consolidated Revenues [Abstract]
Net premiums earned	107.8		120.2	[1]	223.2		255.1	[1]
Net investment income and other income	9.6		16.6	[1]	20.3		33.8	[1]
Total operating revenues	117.5		136.8	[1]	243.5		289.0	[1]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits) and realized investment gains or losses	(160.2)	[3]	(186.9)	[1],[3]	(251.5)	[3]	(308.4)	[1],[3]
Interest charges on intercompany financing arrangements	2.1		2.0		4.2		3.8
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	(56.0)		(65.6)	[1]	(87.9)		(108.4)	[1]
Assets	2,090.2				2,090.2				2,100.7	[1]
Title Insurance Group [Member]
Consolidated Revenues [Abstract]
Net premiums earned	296.3		239.8	[1]	557.3		492.5	[1]
Title, escrow and other fees	107.1		87.2	[1]	201.1		167.4	[1]
Sub-total	403.4		327.1	[1]	758.4		659.9	[1]
Net investment income and other income	7.6		7.5	[1]	14.9		14.7	[1]
Total operating revenues	411.1		334.6	[1]	773.4		674.6	[1]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Income (loss) before income taxes (credits) and realized investment gains or losses	22.5	[3]	5.5	[1],[3]	31.9	[3]	8.1	[1],[3]
Interest charges on intercompany financing arrangements	2.0		1.3		4.0		2.6
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	7.9		1.6	[1]	11.3		2.4	[1]
Assets	993.5				993.5				956.2	[1]
Total of major segments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	1,186.5		1,075.6	[1]	2,320.7		2,172.4	[1]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Consolidated income (loss) before income taxes (credits)	(78.0)		(99.2)	[1]	(79.4)		(129.2)	[1]
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	(31.1)		(38.8)	[1]	(33.6)		(52.4)	[1]
Other sources - net [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	31.7	[4]	36.7	[1],[4]	68.9	[4]	77.2	[1],[4]
Consolidated Income (Loss) Before Taxes (Credits) [Abstract]
Consolidated income (loss) before income taxes (credits)	(2.2)	[4]	(6.1)	[1],[4]	(6.5)	[4]	(7.5)	[1],[4]
Consolidated Income Tax Expense (Credits) [Abstract]
Income tax expense (credits)	(0.8)	[4]	(2.2)	[1],[4]	(2.4)	[4]	(2.8)	[1],[4]
Assets	706.3	[4]			706.3	[4]			973.4	[1],[4]
Consolidation elimination adjustments [Member]
Consolidated Revenues [Abstract]
Consolidated revenues	(16.3)		(14.4)	[1]	(32.5)		(28.6)	[1]
Consolidated Income Tax Expense (Credits) [Abstract]
Assets	$ (425.1)				$ (425.1)				$ (291.2)	[1]

[1] (c) 2011 segment information for General Insurance and RFIG Run-off Business has been reclassified to conform to the 2012 presentation.

[2] (b)Reflects primarily the combination of fully taxable realized investment gains or losses and judgments about the recoverability of deferred tax assets.

[3] (a)Income (loss) before taxes (credits) is reported net of interest charges on intercompany financing arrangements with Old Republic's holding company parent for the following segments: General - $6.9 and $13.8 compared to $6.0 and $11.4 for the quarter and six months ended June 30, 2012 and 2011, respectively; Title - $2.0 and $4.0 compared to $1.3 and $2.6 for the quarter and six months ended June 30, 2012 and 2011, respectively, and RFIG run-off - $2.1 and $4.2 compared to $2.0 and $3.8 for the quarter and six months ended June 30, 2012 and 2011, respectively.

[4] (b)Represents amounts for Old Republic's holding company parent, minor corporate services subsidiaries, and a small life and health insurance operation.