Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Revenue	$ 1,953	$ 1,973	$ 6,144	$ 6,292
Costs of providing services
Salaries and benefits	1,225	1,255	3,802	3,991
Other operating expenses	384	385	1,263	1,169
Depreciation	60	69	191	212
Amortization	71	85	239	285
Restructuring costs	9	0	71	0
Transaction and transformation, net	50	(952)	108	(877)
Total costs of providing services	1,799	842	5,674	4,780
Income from operations	154	1,131	470	1,512
Interest expense	(54)	(50)	(154)	(161)
Other income, net	85	105	205	617
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	185	1,186	521	1,968
Provision for income taxes	(1)	(267)	(63)	(386)
INCOME FROM CONTINUING OPERATIONS	184	919	458	1,582
Income/(loss) from discontinued operations, net of tax	8	(12)	(27)	247
NET INCOME	192	907	431	1,829
Income attributable to non-controlling interests	(2)	(4)	(10)	(9)
NET INCOME ATTRIBUTABLE TO WTW	$ 190	$ 903	$ 421	$ 1,820
Basic earnings per share:
Income from continuing operations per share	$ 1.65	$ 7.10	$ 3.95	$ 12.14
Income/(loss) from discontinued operations per share	0.07	(0.09)	(0.24)	1.90
Basic earnings per share	1.72	7.01	3.71	14.04
Diluted earnings per share:
Income from continuing operations per share	1.65	7.08	3.95	12.10
Income/(loss) from discontinued operations per share	0.07	(0.09)	(0.24)	1.90
Diluted earnings per share	$ 1.72	$ 6.99	$ 3.71	$ 14.00
Comprehensive (loss)/income before non-controlling interests	$ (42)	$ 826	$ (103)	$ 1,831
Comprehensive income attributable to non-controlling interests	(2)	(4)	(10)	(11)
Comprehensive (loss)/income attributable to WTW	$ (44)	$ 822	$ (113)	$ 1,820