Parent Company Information - Condensed Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Earnings (loss) before income taxes									$ 42.8	$ (210.8)	$ (341.8)
Net income (loss) attributable to shareholders	$ 3.1	$ 11.7	$ 6.3	$ (20.9)	$ (18.0)	$ (41.4)	$ (33.5)	$ (92.9)	0.2	(185.8)	(221.3)
Total comprehensive loss									(88.2)	(253.0)	(160.0)
Cushman & Wakefield plc
Condensed Income Statements, Captions [Line Items]
Interest and other income									0.0	2.6	0.0
Interest and other expense									(0.2)	(17.9)	(5.8)
Income (loss) in earnings of subsidiaries									0.4	(170.5)	(215.5)
Earnings (loss) before income taxes									0.2	(185.8)	(221.3)
Net income (loss) attributable to shareholders									0.2	(185.8)	(221.3)
Other comprehensive income (loss) of subsidiaries									(88.4)	(67.2)	61.3
Total comprehensive loss									$ (88.2)	$ (253.0)	$ (160.0)