Business Segments (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment revenue:
Revenue	$ 3,903.7	$ 3,470.3	$ 7,458.9	$ 6,588.0
Reimbursement Revenue	(1,740.4)	(1,595.8)	(3,404.5)	(3,097.2)
Revenue Before Reimbursements	2,163.3	1,874.5	4,054.4	3,490.8
Operating expenses:
Depreciation and amortization	46.3	41.2	88.4	80.5
Operating Income (Loss)	149.8	130.8	203.6	146.2
Equity in earnings (losses)	10.2	14.5	23.8	20.1
Segment Reconciling Items:
Revenue	3,903.7	3,470.3	7,458.9	6,588.0
Total segment operating expenses before restructuring and acquisition charges	2,024.6	1,738.3	3,861.2	3,334.7
Cost of Reimbursable Expense	1,740.4	1,595.8	3,404.5	3,097.2
Segment Operating Expenses before Restructuring and acquisition	3,765.0	3,334.1	7,265.7	6,431.9
Segment Reporting Information Operating Income Before Restructuring Charges	138.7	136.2	193.2	156.1
Restructuring and acquisition charges	(11.1)	5.4	(10.4)	9.9
Operating Income (Loss)	149.8	130.8	203.6	146.2
Assets	9,187.7		9,187.7		$ 9,254.4
Reportable Subsegments [Member]
Segment revenue:
Total segment fee revenue	1,493.5	1,324.3	2,775.0	2,448.3
Operating expenses:
Gross contract vendor and subcontractor costs reimbursement	(668.5)	(543.5)	(1,275.4)	(1,038.5)
Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	2,152.5	1,932.5	4,093.5	3,732.4
Reimbursement Revenue	(1,226.4)	(1,110.0)	(2,408.1)	(2,188.5)
Revenue Before Reimbursements	926.1	822.5	1,685.4	1,543.9
Gross contract costs	(156.6)	(130.4)	(289.7)	(262.2)
Derivative, Gain (Loss) on Derivative, Net	1.3	6.7	4.0	4.0
Total segment fee revenue	768.2	685.4	1,391.7	1,277.7
Operating expenses:
Compensation, operating and administrative expenses	796.9	702.4	1,485.6	1,368.0
Depreciation and amortization	28.3	23.7	52.6	47.2
Operating Expenses, Excluding Reimbursed Expenses	825.2	726.1	1,538.2	1,415.2
Gross contract vendor and subcontractor costs reimbursement	(156.6)	(130.4)	(289.7)	(262.2)
Total fee based segment operating expenses	668.6	595.7	1,248.5	1,153.0
Operating Income (Loss)	100.9	96.4	147.2	128.7
Equity in earnings (losses)	0.4	0.2	0.5	0.4
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	101.3	96.6	147.7	129.1
Segment Reconciling Items:
Revenue	2,152.5	1,932.5	4,093.5	3,732.4
Operating Income (Loss)	100.9	96.4	147.2	128.7
Assets	5,027.8		5,027.8		4,745.4
Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	846.6	721.2	1,630.2	1,324.4
Reimbursement Revenue	(153.0)	(125.5)	(309.0)	(227.4)
Revenue Before Reimbursements	693.6	595.7	1,321.2	1,097.0
Gross contract costs	(305.3)	(248.9)	(582.5)	(480.3)
Total segment fee revenue	388.3	346.8	738.7	616.7
Operating expenses:
Compensation, operating and administrative expenses	683.5	574.6	1,319.7	1,097.6
Depreciation and amortization	11.5	11.1	22.9	21.4
Operating Expenses, Excluding Reimbursed Expenses	695.0	585.7	1,342.6	1,119.0
Gross contract vendor and subcontractor costs reimbursement	(305.3)	(248.9)	(582.5)	(480.3)
Total fee based segment operating expenses	389.7	336.8	760.1	638.7
Operating Income (Loss)	(1.4)	10.0	(21.4)	(22.0)
Equity in earnings (losses)	0.0	0.0	0.0	0.0
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	(1.4)	10.0	(21.4)	(22.0)
Segment Reconciling Items:
Revenue	846.6	721.2	1,630.2	1,324.4
Operating Income (Loss)	(1.4)	10.0	(21.4)	(22.0)
Assets	2,129.0		2,129.0		2,367.5
Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	812.9	743.7	1,524.2	1,370.0
Reimbursement Revenue	(356.2)	(355.9)	(677.8)	(672.4)
Revenue Before Reimbursements	456.7	387.8	846.4	697.6
Gross contract costs	(205.4)	(163.0)	(400.7)	(293.4)
Total segment fee revenue	251.3	224.8	445.7	404.2
Operating expenses:
Compensation, operating and administrative expenses	427.5	360.7	812.5	660.7
Depreciation and amortization	5.8	5.7	11.4	10.5
Operating Expenses, Excluding Reimbursed Expenses	433.3	366.4	823.9	671.2
Gross contract vendor and subcontractor costs reimbursement	(205.4)	(163.0)	(400.7)	(293.4)
Total fee based segment operating expenses	227.9	203.4	423.2	377.8
Operating Income (Loss)	23.4	21.4	22.5	26.4
Equity in earnings (losses)	0.7	0.6	1.0	1.4
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	24.1	22.0	23.5	27.8
Segment Reconciling Items:
Revenue	812.9	743.7	1,524.2	1,370.0
Operating Income (Loss)	23.4	21.4	22.5	26.4
Assets	1,227.2		1,227.2		1,305.0
Investment Management [Member]
Segment revenue:
Revenue	91.7	72.9	211.0	161.2
Reimbursement Revenue	(4.8)	(4.4)	(9.6)	(8.9)
Revenue Before Reimbursements	86.9	68.5	201.4	152.3
Gross contract costs	(1.2)	(1.2)	(2.5)	(2.6)
Total segment fee revenue	85.7	67.3	198.9	149.7
Operating expenses:
Compensation, operating and administrative expenses	70.4	59.4	155.0	127.9
Depreciation and amortization	0.7	0.7	1.5	1.4
Operating Expenses, Excluding Reimbursed Expenses	71.1	60.1	156.5	129.3
Gross contract vendor and subcontractor costs reimbursement	(1.2)	(1.2)	(2.5)	(2.6)
Total fee based segment operating expenses	69.9	58.9	154.0	126.7
Operating Income (Loss)	15.8	8.4	44.9	23.0
Equity in earnings (losses)	9.1	13.7	22.3	18.3
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	24.9	22.1	67.2	41.3
Segment Reconciling Items:
Revenue	91.7	72.9	211.0	161.2
Operating Income (Loss)	15.8	8.4	44.9	23.0
Assets	528.4		528.4		548.6
Segment Reconciling Items [Member]
Segment Reconciling Items:
Assets	275.3		275.3		$ 287.9
Leasing [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	422.9	388.4	727.4	687.4
Segment Reconciling Items:
Revenue	422.9	388.4	727.4	687.4
Leasing [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	72.9	66.8	131.8	115.6
Segment Reconciling Items:
Revenue	72.9	66.8	131.8	115.6
Leasing [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	58.1	51.2	95.9	81.8
Segment Reconciling Items:
Revenue	58.1	51.2	95.9	81.8
Capital Markets [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	117.8	104.7	228.8	203.8
Segment Reconciling Items:
Revenue	117.8	104.7	228.8	203.8
Capital Markets [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	89.9	96.5	179.2	156.5
Segment Reconciling Items:
Revenue	89.9	96.5	179.2	156.5
Capital Markets [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	50.3	36.2	82.7	65.8
Segment Reconciling Items:
Revenue	50.3	36.2	82.7	65.8
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	1,258.4	1,104.6	2,441.9	2,153.7
Segment Reconciling Items:
Revenue	1,258.4	1,104.6	2,441.9	2,153.7
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	392.3	335.2	742.6	639.1
Segment Reconciling Items:
Revenue	392.3	335.2	742.6	639.1
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	541.6	505.4	1,061.4	959.4
Segment Reconciling Items:
Revenue	541.6	505.4	1,061.4	959.4
Project & Development Services [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	274.5	265.0	544.1	555.5
Segment Reconciling Items:
Revenue	274.5	265.0	544.1	555.5
Project & Development Services [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	220.8	160.0	443.4	301.7
Segment Reconciling Items:
Revenue	220.8	160.0	443.4	301.7
Project & Development Services [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	114.1	110.2	201.1	187.9
Segment Reconciling Items:
Revenue	114.1	110.2	201.1	187.9
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	78.9	69.8	151.3	132.0
Segment Reconciling Items:
Revenue	78.9	69.8	151.3	132.0
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	70.7	62.7	133.2	111.5
Segment Reconciling Items:
Revenue	70.7	62.7	133.2	111.5
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	48.8	40.7	83.1	75.1
Segment Reconciling Items:
Revenue	48.8	40.7	83.1	75.1
Advisory Fees [Member] \| Investment Management [Member]
Segment revenue:
Revenue	67.1	64.4	137.0	126.6
Segment Reconciling Items:
Revenue	67.1	64.4	137.0	126.6
Transaction Fees & Other [Member] \| Investment Management [Member]
Segment revenue:
Revenue	6.7	5.1	23.4	19.3
Segment Reconciling Items:
Revenue	6.7	5.1	23.4	19.3
Incentive Fees [Member] \| Investment Management [Member]
Segment revenue:
Revenue	17.9	3.4	50.6	15.3
Segment Reconciling Items:
Revenue	$ 17.9	$ 3.4	$ 50.6	$ 15.3

The total amount of compensation and benefits, and operating, administrative and other expenses.

No definition available.

Name:	jll_CompensationOperatingAndAdministrativeExpenses
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services, less vendor and subcontractor costs, which are reimbursed by the client.

+ References

No definition available.

+ Details

Name:	jll_NetSegmentOperatingExpenses
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Operating Expenses, Excluding expenses directly reimbursed by customers

+ References

No definition available.

+ Details

Name:	jll_OperatingExpensesExcludingReimbursedExpenses
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Operating Income (Loss), Including Income (Loss) from Equity Method Investments

+ References

No definition available.

+ Details

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

- Definition

Revenue Before Reimbursements

+ References

No definition available.

+ Details

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

- Definition

Segment Operating Expenses before Restructuring and Acquisition

+ References

No definition available.

+ Details

Name:	jll_SegmentOperatingExpensesbeforeRestructuringandacquisition
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total segment operating expenses, which includes compensation, operating and administrative expenses, and depreciation and amortization. Does not include restructuring charges.

+ References

No definition available.

+ Details

Name:	jll_SegmentReportingInformationOperatingExpenses
Namespace Prefix:	jll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Operating Income Before Restructuring Charges

+ References

No definition available.

+ Details

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

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cost associated with reimbursable income. This occurs when a services entity incurs expenses on behalf of the client and passes through the cost of reimbursable expenses to a client.

+ References

+ Details

Name:	us-gaap_CostOfReimbursableExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_DepreciationAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate costs related to general contracting services.

+ References

+ Details

Name:	us-gaap_GeneralContractorCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(f))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_OperatingExpensesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_OperatingIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate revenue from real estate operations during the reporting period.

+ References

+ Details

Name:	us-gaap_RealEstateRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants.

+ References

+ Details

Name:	us-gaap_ReimbursementRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_RestructuringCostsAndAssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingInformationRevenueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_ReportableSubsegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_AmericasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_EMEAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_AsiaPacificMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=jll_InvestmentManagementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_MaterialReconcilingItemsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_LeasingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_CapitalMarketsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_PropertyFacilityManagementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_ProjectDevelopmentServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_AdvisoryConsultingandOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_AdvisoryFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_TransactionFeesOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jll_BusinessLineAxis=jll_IncentiveFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: