Debt	9 Months Ended
Sep. 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 September 30, 2014, the Company had $50 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 nine months ended September 30, 2014 was $360 million and $338 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and nine months ended September 30, 2014 was 0.31% and 0.34%, respectively. During the quarter ended September 30, 2014, Aon plc's $600 million 3.50% Notes due September 2015 were classified as Short-term debt and current portion of long-term debt in the Condensed Consolidated Statements of Financial Position as the date of maturity is less than one year. On August 12, 2014, Aon plc issued $350 million of 3.50% Notes due June 2024. The 3.50% Notes due 2024 constitute a further issuance of, and were consolidated to form a single series of debt securities with, the $250 million of 3.50% Notes due June 2024 issued by the Company on May 20, 2014. The 3.50% Notes due June 2024 are unconditionally guaranteed as to the payment of principal and interest by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes. On June 30, 2014, Aon plc transferred €531 million to a trustee pursuant to an agreement related to the repayment of the €500 million of 6.25% Notes due July 2014 and accrued interest. The trustee subsequently disbursed €531 million to the noteholders on July 1, 2014 in payment of principal and accrued interest. The Company remained the primary obligor of the €500 million of 6.25% Notes due July 2014 until the funds were disbursed from the trustee to the bondholders on July 1, 2014. Therefore, the Company extinguished the liability related to this obligation as of July 1, 2014. On May 20, 2014, Aon plc issued $250 million of 3.50% Notes due June 2024 and $550 million of 4.60% Notes due June 2044. The 3.50% Notes due June 2024 and 4.60% Notes due June 2044 are 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, Aon plc issued €500 million of 2.875% Notes due May 2026. The 2.875% Notes due May 2026 are 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 then outstanding €500 million of 6.25% Notes 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 September 30, 2014, the Company had $50 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 nine months ended September 30, 2014 was $360 million and $338 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and nine months ended September 30, 2014 was 0.31% and 0.34%, respectively.

During the quarter ended September 30, 2014, Aon plc's $600 million 3.50% Notes due September 2015 were classified as Short-term debt and current portion of long-term debt in the Condensed Consolidated Statements of Financial Position as the date of maturity is less than one year.

On August 12, 2014, Aon plc issued $350 million of 3.50% Notes due June 2024. The 3.50% Notes due 2024 constitute a further issuance of, and were consolidated to form a single series of debt securities with, the $250 million of 3.50% Notes due June 2024 issued by the Company on May 20, 2014. The 3.50% Notes due June 2024 are unconditionally guaranteed as to the payment of principal and interest by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes.

On June 30, 2014, Aon plc transferred €531 million to a trustee pursuant to an agreement related to the repayment of the €500 million of 6.25% Notes due July 2014 and accrued interest. The trustee subsequently disbursed €531 million to the noteholders on July 1, 2014 in payment of principal and accrued interest. The Company remained the primary obligor of the €500 million of 6.25% Notes due July 2014 until the funds were disbursed from the trustee to the bondholders on July 1, 2014. Therefore, the Company extinguished the liability related to this obligation as of July 1, 2014.

On May 20, 2014, Aon plc issued $250 million of 3.50% Notes due June 2024 and $550 million of 4.60% Notes due June 2044. The 3.50% Notes due June 2024 and 4.60% Notes due June 2044 are 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, Aon plc issued €500 million of 2.875% Notes due May 2026. The 2.875% Notes due May 2026 are 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 then outstanding €500 million of 6.25% Notes due July 2014.