Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Net income	$ 1,239	$ 982
Less: Net income attributable to redeemable and nonredeemable noncontrolling interests	27	17
Net income attributable to Aon shareholders	1,212	965
Other comprehensive income (loss), net of tax:
Change in fair value of financial instruments	(4)	3
Foreign currency translation adjustments	(108)	239
Postretirement benefit obligation	27	47
Total other comprehensive income (loss)	(85)	289
Less: Other comprehensive income attributable to noncontrolling interests	0	0
Total other comprehensive income (loss) attributable to Aon shareholders	(85)	289
Comprehensive income attributable to Aon shareholders	$ 1,127	$ 1,254