Debt	3 Months Ended
Mar. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facilities As of March 31, 2017, Aon had one primary committed credit facility outstanding: its $900 million multi-currency U.S. credit facility expiring in February 2021 (the “2021 Facility”). The Company’s $400 million U.S. credit facility expired in March 2017. The 2021 Facility includes customary representations, warranties and covenants, including financial covenants that require Aon plc to maintain specified ratios of adjusted consolidated earnings before interest, taxes, depreciation, and amortization (“EBITDA”) to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At March 31, 2017, Aon plc did not have borrowings under the 2021 Facility, and was in compliance with all covenants contained therein during the three months ended March 31, 2017. 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, which provides for commercial paper to be issued in an aggregate principal amount of up to €300 million ($324 million at March 31, 2017 exchange rates). 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 $384 million and $329 million of commercial paper outstanding at March 31, 2017 and December 31, 2016, respectively, which is 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 months ended March 31, 2017 and 2016 was $367 million and $177 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three months ended March 31, 2017 and 2016 was 0.12% and 0.11%, respectively.

Debt

Revolving Credit Facilities

As of March 31, 2017, Aon had one primary committed credit facility outstanding: its $900 million multi-currency U.S. credit facility expiring in February 2021 (the “2021 Facility”). The Company’s $400 million U.S. credit facility expired in March 2017.

The 2021 Facility includes customary representations, warranties and covenants, including financial covenants that require Aon plc to maintain specified ratios of adjusted consolidated earnings before interest, taxes, depreciation, and amortization (“EBITDA”) to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At March 31, 2017, Aon plc did not have borrowings under the 2021 Facility, and was in compliance with all covenants contained therein during the three months ended March 31, 2017.

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, which provides for commercial paper to be issued in an aggregate principal amount of up to €300 million ($324 million at March 31, 2017 exchange rates). 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 $384 million and $329 million of commercial paper outstanding at March 31, 2017 and December 31, 2016, respectively, which is 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 months ended March 31, 2017 and 2016 was $367 million and $177 million, respectively. The weighted average interest rate of the commercial paper outstanding for the three months ended March 31, 2017 and 2016 was 0.12% and 0.11%, respectively.