Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Revenue Recognition [Abstract]
Gross revenue and expenses for management services	$ 219.3	$ 174.4

Reimbursement for contract vendor and subcontractor costs that is deducted from gross revenue.

No definition available.

Name:	jll_GrossRevenueAndExpensesForManagementServices
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration