Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Revenue	$ 2,031	$ 2,091	$ 4,191	$ 4,319
Costs of providing services
Salaries and benefits	1,259	1,317	2,577	2,736
Other operating expenses	393	384	879	784
Depreciation	65	72	131	143
Amortization	83	97	168	200
Restructuring costs	56	0	62	0
Transaction and transformation, net	38	51	58	75
Total costs of providing services	1,894	1,921	3,875	3,938
Income from operations	137	170	316	381
Interest expense	(51)	(52)	(100)	(111)
Other income, net	93	74	120	512
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	179	192	336	782
Provision for income taxes	(19)	(75)	(62)	(119)
INCOME FROM CONTINUING OPERATIONS	160	117	274	663
(LOSS)/INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX	(46)	69	(35)	259
NET INCOME	114	186	239	922
Income attributable to non-controlling interests	(5)	(2)	(8)	(5)
NET INCOME ATTRIBUTABLE TO WTW	$ 109	$ 184	$ 231	$ 917
Basic earnings per share:
Income from continuing operations per share	$ 1.38	$ 0.89	$ 2.31	$ 5.07
(Loss)/income from discontinued operations per share	(0.41)	0.53	(0.30)	1.99
Basic earnings per share	0.97	1.42	2.01	7.06
Diluted earnings per share:
Income from continuing operations per share	1.38	0.88	2.31	5.05
(Loss)/income from discontinued operations per share	(0.41)	0.53	(0.30)	1.99
Diluted earnings per share	$ 0.97	$ 1.41	$ 2.01	$ 7.04
Comprehensive (loss)/income before non-controlling interests	$ (130)	$ 219	$ (61)	$ 1,005
Comprehensive income attributable to non-controlling interests	(5)	(2)	(8)	(7)
Comprehensive (loss)/income attributable to WTW	$ (135)	$ 217	$ (69)	$ 998