Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue
Total revenue	$ 2,379	$ 2,349	$ 8,128	$ 8,000
Expenses
Compensation and benefits	1,368	1,392	4,453	4,502
Information technology	120	125	363	363
Premises	76	94	248	283
Depreciation of fixed assets	44	40	124	126
Amortization and impairment of intangible assets	101	100	295	492
Other general expenses	310	336	1,000	1,189
Total operating expenses	2,019	2,087	6,483	6,955
Operating income (loss)	360	262	1,645	1,045
Interest income	1	0	4	5
Interest expense	(78)	(69)	(227)	(208)
Other income (expense)	2	1	8	(17)
Income (loss) from continuing operations before income taxes	285	194	1,430	825
Income tax expense (benefit)	56	39	238	9
Net income from continuing operations	229	155	1,192	816
Net income (loss) from discontinued operations	(1)	(2)	(1)	5
Net income	228	153	1,191	821
Less: Net income attributable to noncontrolling interests	6	6	33	32
Net income attributable to Aon shareholders	$ 222	$ 147	$ 1,158	$ 789
Basic net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	$ 0.94	$ 0.61	$ 4.83	$ 3.18
Discontinued operations (in dollars per share)	0	(0.01)	0	0.02
Net income (in dollars per share)	0.94	0.60	4.83	3.20
Diluted net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	0.93	0.61	4.79	3.17
Discontinued operations (in dollars per share)	0	(0.01)	0	0.02
Net income (in dollars per share)	$ 0.93	$ 0.60	$ 4.79	$ 3.19
Weighted average ordinary shares outstanding - basic (in shares)	236.9	244.0	239.9	246.2
Weighted average ordinary shares outstanding - diluted (in shares)	239.1	245.6	241.9	247.7