Claims, Lawsuits And Other Contingencies	3 Months Ended
Mar. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Claims, Lawsuits, and Other Contingencies	Claims, Lawsuits and Other Contingencies Errors and Omissions Claims The Company and its subsidiaries, particularly Marsh and Mercer, are subject to a significant number of claims, lawsuits and proceedings in the ordinary course of business. Such claims and lawsuits consist principally of alleged errors and omissions in connection with the performance of professional services, including the placement of insurance, the provision of actuarial services for corporate and public sector clients, and the provision of consulting services relating to the drafting and interpretation of trust deeds and other documentation governing pension plans. Certain of these claims, particularly in the U.S. and the U.K., seek damages, including punitive and treble damages, in amounts that could, if awarded, be significant. In establishing liabilities for errors and omissions claims in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies), the Company utilizes case level reviews by inside and outside counsel and an internal actuarial analysis to estimate potential losses. A liability is established when a loss is both probable and reasonably estimable. The liability is reviewed quarterly and adjusted as developments warrant. In many cases, the Company has not recorded a liability, other than for legal fees to defend the claim, because we are unable, at the present time, to make a determination that a loss is both probable and reasonably estimable. To the extent that expected losses exceed our deductible in any policy year, the Company also records an asset for the amount that we expect to recover under any available third-party insurance programs. The Company has varying levels of third-party insurance coverage, with policy limits and coverage terms varying significantly by policy year. Governmental Inquiries and Related Claims In January 2005, the Company and its subsidiary Marsh Inc. entered into a settlement agreement with the New York State Attorney General (“NYAG”) and the New York State Insurance Department to settle a civil complaint and related citation regarding Marsh's use of market service agreements with various insurance companies. The parties subsequently entered into an amended and restated settlement agreement in February 2010 that restored a level playing field for Marsh. Numerous private party lawsuits based on similar allegations to those made in the NYAG complaint were commenced against the Company, one or more of its subsidiaries, and their current and former directors and officers. Most of these matters have been resolved. Two actions instituted by policyholders against the Company, Marsh and certain Marsh subsidiaries remain pending in federal court. Our activities are regulated under the laws of the United States and its various states, the European Union and its member states, and the other jurisdictions in which the Company operates. In the ordinary course of business the Company is also subject to investigations, lawsuits and/or other regulatory actions undertaken by governmental authorities. Other Contingencies-Guarantees In connection with its acquisition of U.K.-based Sedgwick Group in 1998, the Company acquired several insurance underwriting businesses that were already in run-off, including River Thames Insurance Company Limited (“River Thames”), which the Company sold in 2001. Sedgwick guaranteed payment of claims on certain policies underwritten through the Institute of London Underwriters (the “ILU”) by River Thames. The policies covered by this guarantee are reinsured up to £40 million by a related party of River Thames. Payment of claims under the reinsurance agreement is collateralized by segregated assets held in a trust. As of March 31, 2013, the reinsurance coverage exceeded the best estimate of the projected liability of the policies covered by the guarantee. To the extent River Thames or the reinsurer is unable to meet its obligations under those policies, a claimant may seek to recover from us under the guarantee. From 1980 to 1983, the Company owned indirectly the English & American Insurance Company (“E&A”), which was a member of the ILU. The ILU required the Company to guarantee a portion of E&A's obligations. After E&A became insolvent in 1993, the ILU agreed to discharge the guarantee in exchange for the Company's agreement to post an evergreen letter of credit that is available to pay claims by policyholders on certain E&A policies issued through the ILU and incepting between July 3, 1980 and October 6, 1983. Certain claims have been paid under the letter of credit and we anticipate that additional claimants may seek to recover against the letter of credit. Kroll-related Matters Under the terms of a stock purchase agreement with Altegrity, Inc. (“Altegrity”) related to Altegrity's purchase of Kroll from the Company in August 2010, a copy of which is attached as an exhibit to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2010, the Company agreed to provide a limited indemnity to Altegrity with respect to certain Kroll-related litigation and regulatory matters. ********** The pending proceedings and other matters described in this Note 15 on Claims, Lawsuits and Other Contingencies may expose the Company or its subsidiaries to liability for significant monetary damages and other forms of relief. Where a loss is both probable and reasonably estimable, the Company establishes liabilities in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies). Except as described above, the Company is not able at this time to provide a reasonable estimate of the range of possible loss attributable to these matters or the impact they may have on the Company's consolidated results of operations, financial position or cash flows. This is primarily because these matters are still developing and involve complex issues subject to inherent uncertainty. Adverse determinations in one or more of these matters could have a material impact on the Company's consolidated results of operations, financial condition or cash flows in a future period.

Claims, Lawsuits and Other Contingencies

Errors and Omissions Claims

The Company and its subsidiaries, particularly Marsh and Mercer, are subject to a significant number of claims, lawsuits and proceedings in the ordinary course of business. Such claims and lawsuits consist principally of alleged errors and omissions in connection with the performance of professional services, including the placement of insurance, the provision of actuarial services for corporate and public sector clients, and the provision of consulting services relating to the drafting and interpretation of trust deeds and other documentation governing pension plans. Certain of these claims, particularly in the U.S. and the U.K., seek damages, including punitive and treble damages, in amounts that could, if awarded, be significant. In establishing liabilities for errors and omissions claims in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies), the Company utilizes case level reviews by inside and outside counsel and an internal actuarial analysis to estimate potential losses. A liability is established when a loss is both probable and reasonably estimable. The liability is reviewed quarterly and adjusted as developments warrant. In many cases, the Company has not recorded a liability, other than for legal fees to defend the claim, because we are unable, at the present time, to make a determination that a loss is both probable and reasonably estimable.

To the extent that expected losses exceed our deductible in any policy year, the Company also records an asset for the amount that we expect to recover under any available third-party insurance programs. The Company has varying levels of third-party insurance coverage, with policy limits and coverage terms varying significantly by policy year.

Governmental Inquiries and Related Claims

In January 2005, the Company and its subsidiary Marsh Inc. entered into a settlement agreement with the New York State Attorney General (“NYAG”) and the New York State Insurance Department to settle a civil complaint and related citation regarding Marsh's use of market service agreements with various insurance companies. The parties subsequently entered into an amended and restated settlement agreement in February 2010 that restored a level playing field for Marsh.

Numerous private party lawsuits based on similar allegations to those made in the NYAG complaint were commenced against the Company, one or more of its subsidiaries, and their current and former directors and officers. Most of these matters have been resolved. Two actions instituted by policyholders against the Company, Marsh and certain Marsh subsidiaries remain pending in federal court.

Our activities are regulated under the laws of the United States and its various states, the European Union and its member states, and the other jurisdictions in which the Company operates. In the ordinary course of business the Company is also subject to investigations, lawsuits and/or other regulatory actions undertaken by governmental authorities.

Other Contingencies-Guarantees

In connection with its acquisition of U.K.-based Sedgwick Group in 1998, the Company acquired several insurance underwriting businesses that were already in run-off, including River Thames Insurance Company Limited (“River Thames”), which the Company sold in 2001. Sedgwick guaranteed payment of claims on certain policies underwritten through the Institute of London Underwriters (the “ILU”) by River Thames. The policies covered by this guarantee are reinsured up to £40 million by a related party of River Thames. Payment of claims under the reinsurance agreement is collateralized by segregated assets held in a trust. As of March 31, 2013, the reinsurance coverage exceeded the best estimate of the projected liability of the policies covered by the guarantee. To the extent River Thames or the reinsurer is unable to meet its obligations under those policies, a claimant may seek to recover from us under the guarantee.

From 1980 to 1983, the Company owned indirectly the English & American Insurance Company (“E&A”), which was a member of the ILU. The ILU required the Company to guarantee a portion of E&A's obligations. After E&A became insolvent in 1993, the ILU agreed to discharge the guarantee in exchange for the Company's agreement to post an evergreen letter of credit that is available to pay claims by policyholders on certain E&A policies issued through the ILU and incepting between July 3, 1980 and October 6, 1983. Certain claims have been paid under the letter of credit and we anticipate that additional claimants may seek to recover against the letter of credit.

Kroll-related Matters

Under the terms of a stock purchase agreement with Altegrity, Inc. (“Altegrity”) related to Altegrity's purchase of Kroll from the Company in August 2010, a copy of which is attached as an exhibit to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2010, the Company agreed to provide a limited indemnity to Altegrity with respect to certain Kroll-related litigation and regulatory matters.

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The pending proceedings and other matters described in this Note 15 on Claims, Lawsuits and Other Contingencies may expose the Company or its subsidiaries to liability for significant monetary damages and other forms of relief. Where a loss is both probable and reasonably estimable, the Company establishes liabilities in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies). Except as described above, the Company is not able at this time to provide a reasonable estimate of the range of possible loss attributable to these matters or the impact they may have on the Company's consolidated results of operations, financial position or cash flows. This is primarily because these matters are still developing and involve complex issues subject to inherent uncertainty. Adverse determinations in one or more of these matters could have a material impact on the Company's consolidated results of operations, financial condition or cash flows in a future period.