Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue
Revenue	$ 2,497	$ 2,606	$ 5,716	$ 5,749
Income (expense) from non-guarantor subsidiaries
Compensation and benefits	1,361	1,501	2,883	3,085
Information technology	107	126	218	243
Premises	74	85	147	172
Depreciation of fixed assets	41	40	82	80
Amortization of intangible assets	58	97	155	194
Other general expense	262	344	604	690
Total operating expenses	1,903	2,193	4,089	4,464
Operating income	594	413	1,627	1,285
Interest income	0	1	2	3
Interest expense	(89)	(77)	(172)	(149)
Other income (expense)	(10)	6	19	6
Income from continuing operations before income taxes	495	343	1,476	1,145
Income tax expense	85	56	274	182
Net income from continuing operations	410	287	1,202	963
Net income from discontinued operations	1	0	0	0
Net income	411	287	1,202	963
Less: Net income attributable to noncontrolling interests	13	10	32	27
Net income attributable to Aon shareholders	$ 398	$ 277	$ 1,170	$ 936
Basic net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	$ 1.71	$ 1.15	$ 5.02	$ 3.88
Discontinued operations (in dollars per share)	0	0	0	0
Net income (in dollars per share)	1.71	1.15	5.02	3.88
Diluted net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	1.70	1.14	5.00	3.85
Discontinued operations (in dollars per share)	0	0	0	0
Net income (in dollars per share)	$ 1.70	$ 1.14	$ 5.00	$ 3.85
Weighted average ordinary shares outstanding - basic (in shares)	232.7	240.6	233.0	241.4
Weighted average ordinary shares outstanding - diluted (in shares)	233.6	242.8	234.1	243.2