Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Revenue	$ 2,160	$ 2,228
Costs of providing services
Salaries and benefits	1,318	1,419
Other operating expenses	486	400
Depreciation	66	71
Amortization	85	103
Restructuring costs	6	0
Transaction and transformation, net	20	24
Total costs of providing services	1,981	2,017
Income from operations	179	211
Interest expense	(49)	(59)
Other income, net	27	438
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	157	590
Provision for income taxes	(43)	(44)
INCOME FROM CONTINUING OPERATIONS	114	546
Income from discontinued operations, net of tax	11	190
NET INCOME	125	736
Income attributable to non-controlling interests	(3)	(3)
NET INCOME ATTRIBUTABLE TO WTW	$ 122	$ 733
Basic earnings per share:
Income from continuing operations per share	$ 0.94	$ 4.18
Income from discontinued operations per share	0.09	1.46
Basic earnings per share	1.03	5.64
Diluted earnings per share:
Income from continuing operations per share	0.94	4.17
Income from discontinued operations per share	0.09	1.46
Diluted earnings per share	$ 1.03	$ 5.63
Comprehensive income before non-controlling interests	$ 69	$ 786
Comprehensive income attributable to non-controlling interests	(3)	(5)
Comprehensive income attributable to WTW	$ 66	$ 781