Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Income Statement [Abstract]
Revenue	$ 2,223	$ 2,341
Costs of providing services
Salaries and benefits	1,324	1,342
Other operating expenses	365	457
Depreciation	54	59
Amortization	48	60
Restructuring costs	0	18
Transaction and transformation	0	125
Total costs of providing services	1,791	2,061
Income from operations	432	280
Interest expense	(65)	(64)
Other (loss)/income, net	(64)	26
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND INTEREST IN EARNINGS OF ASSOCIATES	303	242
Provision for income taxes	(65)	(48)
INCOME FROM OPERATIONS BEFORE INTEREST IN EARNINGS OF ASSOCIATES	238	194
Interests in earnings of associates, net of tax	1	0
NET INCOME	239	194
Income attributable to non-controlling interests	(4)	(4)
NET INCOME ATTRIBUTABLE TO WTW	$ 235	$ 190
Basic earnings per share:
Basic earnings per share	$ 2.34	$ 1.84
Diluted earnings per share:
Diluted earnings per share	$ 2.33	$ 1.83
Comprehensive income before non-controlling interests	$ 462	$ 145
Comprehensive income attributable to non-controlling interests	(4)	(4)
Comprehensive income attributable to WTW	$ 458	$ 141