Debt	6 Months Ended
Jun. 30, 2015
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facilities As of December 31, 2014, Aon plc had two primary committed credit facilities outstanding: its $400 million U.S. credit facility expiring in March 2017 (the "2017 Facility") and its €650 million ($726 million based on exchange rates at June 30, 2015) European credit facility expiring in October 2015 (the "2015 Facility"). Aon Corporation entered into the 2015 Facility on October 15, 2010 (Aon plc became a borrower under such facility on April 29, 2013) and Aon plc entered into the 2017 Facility on March 20, 2012. On February 2, 2015, Aon plc replaced the 2015 Facility with a new $900 million multi-currency U.S. credit facility expiring in February 2020 (the "2020 Facility"). Each of these facilities included customary representations, warranties and covenants, including financial covenants that require Aon plc to maintain specified ratios of adjusted consolidated EBITDA to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At June 30, 2015, Aon plc did not have borrowings under either the 2017 Facility or the 2020 Facility, and was in compliance with these financial covenants and all other covenants contained therein during the six months ended June 30, 2015. Commercial Paper Aon Corporation, a wholly-owned subsidiary of Aon plc, has established a U.S. commercial paper program, which provides for commercial paper to be issued in an aggregate principal amount of up to $900 million, and Aon plc has established a European multi-currency commercial paper program that provides for commercial paper to be issued in an aggregate principal amount of up to €300 million. The U.S. commercial paper program is fully and unconditionally guaranteed by Aon plc and the European commercial paper program is fully and unconditionally guaranteed by Aon Corporation. In the aggregate, the Company had $125 million and $168 million of commercial paper outstanding at June 30, 2015 and December 31, 2014, respectively, which was included in Short-term debt and current portion of long-term debt in the Company's Condensed Consolidated Statements of Financial Position. The weighted average commercial paper outstanding for the three and six months ended June 30, 2015 was $359 million and $338 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and six months ended June 30, 2015 was 0.46% and 0.48%, respectively. Notes On May 20, 2015, the Aon plc issued $600 million of 4.750% Senior Notes due May 2045. The 4.750% Notes due May 2045 are fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes.

Debt

Revolving Credit Facilities

As of December 31, 2014, Aon plc had two primary committed credit facilities outstanding: its $400 million U.S. credit facility expiring in March 2017 (the "2017 Facility") and its €650 million ($726 million based on exchange rates at June 30, 2015) European credit facility expiring in October 2015 (the "2015 Facility"). Aon Corporation entered into the 2015 Facility on October 15, 2010 (Aon plc became a borrower under such facility on April 29, 2013) and Aon plc entered into the 2017 Facility on March 20, 2012. On February 2, 2015, Aon plc replaced the 2015 Facility with a new $900 million multi-currency U.S. credit facility expiring in February 2020 (the "2020 Facility"). Each of these facilities included customary representations, warranties and covenants, including financial covenants that require Aon plc to maintain specified ratios of adjusted consolidated EBITDA to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At June 30, 2015, Aon plc did not have borrowings under either the 2017 Facility or the 2020 Facility, and was in compliance with these financial covenants and all other covenants contained therein during the six months ended June 30, 2015.

Commercial Paper

Aon Corporation, a wholly-owned subsidiary of Aon plc, has established a U.S. commercial paper program, which provides for commercial paper to be issued in an aggregate principal amount of up to $900 million, and Aon plc has established a European multi-currency commercial paper program that provides for commercial paper to be issued in an aggregate principal amount of up to €300 million. The U.S. commercial paper program is fully and unconditionally guaranteed by Aon plc and the European commercial paper program is fully and unconditionally guaranteed by Aon Corporation. In the aggregate, the Company had $125 million and $168 million of commercial paper outstanding at June 30, 2015 and December 31, 2014, respectively, which was included in Short-term debt and current portion of long-term debt in the Company's Condensed Consolidated Statements of Financial Position. The weighted average commercial paper outstanding for the three and six months ended June 30, 2015 was $359 million and $338 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three and six months ended June 30, 2015 was 0.46% and 0.48%, respectively.

Notes

On May 20, 2015, the Aon plc issued $600 million of 4.750% Senior Notes due May 2045. The 4.750% Notes due May 2045 are fully and unconditionally guaranteed by Aon Corporation. The Company used the proceeds of the issuance for general corporate purposes.