Fiduciary Assets And Liabilities	6 Months Ended
Jun. 30, 2012
Fiduciary Assets And Liabilities [Abstract]
Fiduciary Assets And Liabilities	Fiduciary Assets and Liabilities In its capacity as an insurance broker or agent, the Company collects premiums from insureds and, after deducting its commissions, remits the premiums to the respective insurance underwriters. The Company also collects claims or refunds from underwriters on behalf of insureds. Unremitted insurance premiums and claims proceeds are held by the Company in a fiduciary capacity. Risk and Insurance Services revenue includes interest on fiduciary funds of $21 million and $22 million for the six-month periods ended June 30, 2012 and 2011, respectively. The Consulting segment recorded fiduciary interest income of $1 million for the the six-month period ended June 30, 2012 and $2 million for the same period in 2011. Since fiduciary assets are not available for corporate use, they are shown in the consolidated balance sheets as an offset to fiduciary liabilities. Fiduciary assets include approximately $19 million and $62 million of fixed income securities classified as available for sale at June 30, 2012 and December 31, 2011, respectively. Unrealized gains or losses from available for sale securities are recorded in other comprehensive income until the securities are disposed of, mature or a loss is recognized as an other than temporary impairment. Unrealized gains, net of tax, were $0 million and $2 million at June 30, 2012 and December 31, 2011, respectively. Net uncollected premiums and claims and the related payables amounted to $11 billion at June 30, 2012 and $9 billion at December 31, 2011. The Company is not a principal to the contracts under which the right to receive premiums or the right to receive reimbursement of insured losses arises. Net uncollected premiums and claims and the related payables are, therefore, not assets and liabilities of the Company and are not included in the accompanying consolidated balance sheets. In certain instances, the Company advances premiums, refunds or claims to insurance underwriters or insureds prior to collection. These advances are made from corporate funds and are reflected in the accompanying consolidated balance sheets as receivables. Mercer manages approximately $17 billion of assets in trusts or funds for which Mercer’s management or trustee fee is considered a variable interest. Mercer is not the primary beneficiary of these trusts or funds. Mercer’s only variable interest in any of these trusts or funds is its unpaid fees, if any. Mercer’s maximum exposure to loss of its interests is, therefore, limited to collection of its fees.

Fiduciary Assets and Liabilities

In its capacity as an insurance broker or agent, the Company collects premiums from insureds and, after deducting its commissions, remits the premiums to the respective insurance underwriters. The Company also collects claims or refunds from underwriters on behalf of insureds. Unremitted insurance premiums and claims proceeds are held by the Company in a fiduciary capacity. Risk and Insurance Services revenue includes interest on fiduciary funds of $21 million and $22 million for the six-month periods ended June 30, 2012 and 2011, respectively. The Consulting segment recorded fiduciary interest income of $1 million for the the six-month period ended June 30, 2012 and $2 million for the same period in 2011. Since fiduciary assets are not available for corporate use, they are shown in the consolidated balance sheets as an offset to fiduciary liabilities.

Fiduciary assets include approximately $19 million and $62 million of fixed income securities classified as available for sale at June 30, 2012 and December 31, 2011, respectively. Unrealized gains or losses from available for sale securities are recorded in other comprehensive income until the securities are disposed of, mature or a loss is recognized as an other than temporary impairment. Unrealized gains, net of tax, were $0 million and $2 million at June 30, 2012 and December 31, 2011, respectively.

Net uncollected premiums and claims and the related payables amounted to $11 billion at June 30, 2012 and $9 billion at December 31, 2011. The Company is not a principal to the contracts under which the right to receive premiums or the right to receive reimbursement of insured losses arises. Net uncollected premiums and claims and the related payables are, therefore, not assets and liabilities of the Company and are not included in the accompanying consolidated balance sheets.

In certain instances, the Company advances premiums, refunds or claims to insurance underwriters or insureds prior to collection. These advances are made from corporate funds and are reflected in the accompanying consolidated balance sheets as receivables.

Mercer manages approximately $17 billion of assets in trusts or funds for which Mercer’s management or trustee fee is considered a variable interest. Mercer is not the primary beneficiary of these trusts or funds. Mercer’s only variable interest in any of these trusts or funds is its unpaid fees, if any. Mercer’s maximum exposure to loss of its interests is, therefore, limited to collection of its fees.