Parent Company Information - Condensed Statements of Cash Flows (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
Cash flows from operating activities
Net income (loss)	$ 3.1	$ 11.7	$ 6.3	$ (20.9)	$ (18.0)	$ (41.4)	$ (33.5)	$ (92.9)	$ 0.2	$ (185.8)	$ (221.3)
Reconciliation of net income (loss) to net cash used in operating activities:
Unrealized foreign exchange gain									(5.9)	5.6	(2.6)
Trade and other receivables									(38.9)	(235.5)	(173.4)
Increase in other liabilities									(164.8)	(216.8)	58.8
Net cash (used in) provided by operating activities									269.3	(2.2)	4.4
Cash flows from investing activities:
Net cash used in investing activities									(274.9)	(218.0)	(143.2)
Cash flows from financing activities:
Proceeds from issuance of common stock									0.3	9.0	23.4
Proceeds from initial public offering, net of underwriting									0.0	831.4	0.0
Proceeds from private placement									0.0	179.5	0.0
Payments of initial offering and private placement costs									0.0	(17.3)	0.0
Other financing activities, net									(2.3)	(7.3)	2.3
Net cash (used in) provided by financing activities									(89.6)	725.9	167.7
Change in cash, cash equivalents and restricted cash									(95.2)	505.7	28.9
Cash, cash equivalents and restricted cash, beginning of the year				965.4				467.9	965.4	467.9	424.8
Cash, cash equivalents and restricted cash, end of the year	872.3				965.4				872.3	965.4	467.9
Supplemental disclosure of non-cash activities:
Stock-based compensation									61.3	81.9	52.4
Cushman & Wakefield plc
Cash flows from operating activities
Net income (loss)									0.2	(185.8)	(221.3)
Reconciliation of net income (loss) to net cash used in operating activities:
(Income) loss in earnings of subsidiaries									(0.4)	170.5	215.5
Unrealized foreign exchange gain									0.0	0.0	0.0
Trade and other receivables									0.0	(128.7)	0.0
Increase in trade and other payables									0.0	20.0	0.5
Increase in other liabilities									0.0	6.2	5.8
Net cash (used in) provided by operating activities									(0.2)	(117.8)	0.5
Cash flows from investing activities:
Investment in subsidiaries									0.0	(865.5)	(22.5)
Net cash used in investing activities									0.0	(865.5)	(22.5)
Cash flows from financing activities:
Proceeds from issuance of common stock									0.3	0.0	22.0
Proceeds from initial public offering, net of underwriting									0.0	831.4	0.0
Proceeds from private placement									0.0	179.5	0.0
Payments of initial offering and private placement costs									0.0	(17.3)	0.0
Other financing activities, net									0.1	0.2	0.0
Net cash (used in) provided by financing activities									0.4	993.8	22.0
Change in cash, cash equivalents and restricted cash									0.2	10.5	0.0
Cash, cash equivalents and restricted cash, beginning of the year				$ 10.5				$ 0.0	10.5	0.0	0.0
Cash, cash equivalents and restricted cash, end of the year	$ 10.7				$ 10.5				10.7	10.5	0.0
Supplemental disclosure of non-cash activities:
Accretion of deferred purchase obligation									0.0	19.7	20.8
Capital contributions to subsidiaries									0.0	0.0	6.2
Stock-based compensation									61.3	51.4	43.3
Acquisition and disposal of non-controlling interest									$ 0.0	$ 0.0	$ 2.0