Dispositions (Income Statement Data) (Details) (USD $) In Millions, except Per Share data	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Dispositions
Revenue		$ 163		$ 325
Expense		146		293
Net operating income		17		32
Income Tax				15
Income from Kroll operations, net of tax		17		17
Income (loss) from discontinued operations, net of tax		17		17
Disposals of discontinued operations	8	(8)	8	7
Income tax (credit) expense	5	(262)	(7)	(225)
Disposals of discontinued operations, net of tax	3	254	15	232
Discontinued operations net of tax	$ 3	$ 271	$ 15	$ 249
Discontinued operations, net of tax per basic share	$ 0.00	$ 0.49	$ 0.02	$ 0.46
Discontinued operations, net of tax per diluted share	$ 0.00	$ 0.49	$ 0.03	$ 0.45

Discontinued Subsidiary Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax

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Pretax gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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Gain (loss) after tax expense or benefit, not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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Pretax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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After tax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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Income tax expense or benefit attributable to Income or Loss from discontinued operations during the phase-out period.

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Tax expense or benefit on the gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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Amount of operating expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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This element represents the overall income (loss) from a disposal group apportioned to the parent that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount which may be allocable to noncontrolling interests, if any. Includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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The amount of net income (loss) derived from discontinued operations during the period, net of related tax effect, per each share of common stock or unit outstanding during the reporting period.

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The amount of net income or loss derived from discontinued operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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