Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue
Total revenue	$ 2,606	$ 2,561	$ 5,749	$ 5,651
Expenses
Compensation and benefits	1,501	1,494	3,085	3,110
Information technology	126	123	243	238
Premises	85	96	172	189
Depreciation of fixed assets	40	47	80	86
Amortization and impairment of intangible assets	97	282	194	392
Other general expenses	344	535	690	853
Total operating expenses	2,193	2,577	4,464	4,868
Operating income (loss)	413	(16)	1,285	783
Interest income	1	1	3	5
Interest expense	(77)	(69)	(149)	(139)
Other income (expense)	6	(3)	6	(18)
Income (loss) from continuing operations before income taxes	343	(87)	1,145	631
Income tax expense (benefit)	56	(144)	182	(30)
Net income from continuing operations	287	57	963	661
Net income from discontinued operations	0	1	0	7
Net income	287	58	963	668
Less: Net income attributable to noncontrolling interests	10	10	27	26
Net income attributable to Aon shareholders	$ 277	$ 48	$ 936	$ 642
Basic net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	$ 1.15	$ 0.19	$ 3.88	$ 2.57
Discontinued operations (in dollars per share)	0	0.01	0	0.03
Net income (in dollars per share)	1.15	0.20	3.88	2.60
Diluted net income per share attributable to Aon shareholders
Continuing operations (in dollars per share)	1.14	0.19	3.85	2.55
Discontinued operations (in dollars per share)	0	0	0	0.03
Net income (in dollars per share)	$ 1.14	$ 0.19	$ 3.85	$ 2.58
Weighted average ordinary shares outstanding - basic (in shares)	240.6	246.0	241.4	247.2
Weighted average ordinary shares outstanding - diluted (in shares)	242.8	247.4	243.2	248.8