Debt	6 Months Ended
Jun. 30, 2014
Debt Disclosure [Abstract]
Debt	Debt The Company uses proceeds from the commercial paper market from time to time in order to meet short-term working capital needs and to retire other debt obligations. At June 30, 2014, the Company had $107 million in commercial paper outstanding compared to no commercial paper outstanding at December 31, 2013. The weighted average commercial paper outstanding for the three and six months ended June 30, 2014 was $447 million and $326 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and six months ended June 30, 2014 was 0.38% and 0.36%, respectively. On June 30, 2014, the Company transferred €531 million to a trustee pursuant to an agreement related to the repayment of the 6.25% €500 million debt securities due July 2014 and accrued interest. The trustee subsequently disbursed €531 million to the bondholders on July 1, 2014 in payment of principal and accrued interest. The Company remained the primary obligor of the 6.25% €500 million debt securities due July 2014 until the funds were disbursed from the trustee to the bondholders on July 1, 2014. Therefore, the Company did not extinguish the liability related to this obligation at June 30, 2014. As of June 30, 2014, the Company had $681 million of debt related to this obligation recorded in Short-term debt and current portion of long-term debt, $42 million of interest accrued in Accounts payable and accrued liabilities, and a $723 million deposit to trustee recorded within Other current assets on the Condensed Consolidated Statements of Financial Position. The Company reflected the cash payment to the trustee for the principal amount as a financing activity and the accrued interest amount as an operating activity on the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2014. On May 20, 2014, the Company issued $250 million in aggregate principal amount of 3.50% Notes Due 2024 and $550 million in aggregate principal amount of 4.60% Notes Due 2044. The 3.50% Notes Due 2024 and 4.60% Notes Due 2044 were issued by Aon plc and fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance to repay commercial paper borrowings and for general corporate purposes. On May 7, 2014, the Company issued €500 million in aggregate principal amount of 2.875% Notes Due 2026. The 2.875% Notes Due 2026 were issued by Aon plc and fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes, including the repayment at maturity of the Company's outstanding 6.25% €500 million debt securities due July 2014.

Debt

The Company uses proceeds from the commercial paper market from time to time in order to meet short-term working capital needs and to retire other debt obligations. At June 30, 2014, the Company had $107 million in commercial paper outstanding compared to no commercial paper outstanding at December 31, 2013. The weighted average commercial paper outstanding for the three and six months ended June 30, 2014 was $447 million and $326 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and six months ended June 30, 2014 was 0.38% and 0.36%, respectively.

On June 30, 2014, the Company transferred €531 million to a trustee pursuant to an agreement related to the repayment of the 6.25% €500 million debt securities due July 2014 and accrued interest. The trustee subsequently disbursed €531 million to the bondholders on July 1, 2014 in payment of principal and accrued interest. The Company remained the primary obligor of the 6.25% €500 million debt securities due July 2014 until the funds were disbursed from the trustee to the bondholders on July 1, 2014. Therefore, the Company did not extinguish the liability related to this obligation at June 30, 2014. As of June 30, 2014, the Company had $681 million of debt related to this obligation recorded in Short-term debt and current portion of long-term debt, $42 million of interest accrued in Accounts payable and accrued liabilities, and a $723 million deposit to trustee recorded within Other current assets on the Condensed Consolidated Statements of Financial Position. The Company reflected the cash payment to the trustee for the principal amount as a financing activity and the accrued interest amount as an operating activity on the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2014.

On May 20, 2014, the Company issued $250 million in aggregate principal amount of 3.50% Notes Due 2024 and $550 million in aggregate principal amount of 4.60% Notes Due 2044. The 3.50% Notes Due 2024 and 4.60% Notes Due 2044 were issued by Aon plc and fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance to repay commercial paper borrowings and for general corporate purposes.

On May 7, 2014, the Company issued €500 million in aggregate principal amount of 2.875% Notes Due 2026. The 2.875% Notes Due 2026 were issued by Aon plc and fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes, including the repayment at maturity of the Company's outstanding 6.25% €500 million debt securities due July 2014.