Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue
Total revenue	$ 2,385	$ 2,379	$ 8,101	$ 8,128
Expenses
Compensation and benefits	1,387	1,368	4,270	4,453
Information technology	107	120	325	363
Premises	70	76	217	248
Depreciation of fixed assets	42	44	124	124
Amortization of intangible assets	50	101	205	295
Other general expense	288	310	892	1,000
Total operating expenses	1,944	2,019	6,033	6,483
Operating income	441	360	2,068	1,645
Interest income	3	1	5	4
Interest expense	(80)	(78)	(252)	(227)
Other income (expense)	(1)	2	18	8
Income from continuing operations before income taxes	363	285	1,839	1,430
Income tax expense	82	56	356	238
Net income from continuing operations	281	229	1,483	1,192
Net income (loss) from discontinued operations	1	(1)	1	(1)
Net income	282	228	1,484	1,191
Less: Net income attributable to noncontrolling interests	7	6	39	33
Net income attributable to Aon shareholders	$ 275	$ 222	$ 1,445	$ 1,158
Basic net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	$ 1.18	$ 0.94	$ 6.21	$ 4.83
Discontinued operations (in dollars per share)	0	0	0	0
Net income (in dollars per share)	1.18	0.94	6.21	4.83
Diluted net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	1.18	0.93	6.18	4.79
Discontinued operations (in dollars per share)	0	0	0	0
Net income (in dollars per share)	$ 1.18	$ 0.93	$ 6.18	$ 4.79
Weighted average ordinary shares outstanding - basic (in shares)	232.6	236.9	232.8	239.9
Weighted average ordinary shares outstanding - diluted (in shares)	233.5	239.1	233.9	241.9