Business Segments (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Reimbursement Revenues	$ 1,841.9	$ 1,918.3	$ 3,704.9	$ 3,777.3
Segment revenue:
Revenue	3,670.4	4,266.5	7,766.4	8,087.1
Revenue Before Reimbursements	1,828.5	2,348.2	4,061.5	4,309.8
Operating expenses:
Depreciation and amortization	56.9	45.5	111.9	92.0
Operating Income (Loss)	10.8	150.1	75.4	175.5
Equity in earnings (losses)	14.7	10.2	(13.6)	15.2
Segment Reconciling Items:
Revenue	3,670.4	4,266.5	7,766.4	8,087.1
Total segment operating expenses before restructuring and acquisition charges	1,789.5	2,172.4	3,943.8	4,090.0
Cost of Reimbursable Expenses	1,841.9	1,918.3	3,704.9	3,777.3
Segment Operating Expenses before Restructuring and acquisition	3,631.4	4,090.7	7,648.7	7,867.3
Segment Reporting Information Operating Income Before Restructuring Charges	39.0	175.8	117.7	219.8
Restructuring and acquisition charges	28.2	25.7	42.3	44.3
Operating Income (Loss)	10.8	150.1	75.4	175.5
Assets	12,810.5		12,810.5		$ 13,672.6
Reportable Subsegments [Member]
Segment revenue:
Real Estate Revenues, Net	1,244.9	1,630.0	2,750.1	2,949.1
Operating expenses:
Gross contract vendor and subcontractor costs reimbursement	575.0	713.4	1,304.4	1,356.0
Reportable Subsegments [Member] \| Americas [Member]
Segment Reporting Information [Line Items]
Reimbursement Revenues	1,345.0	1,403.1	2,738.5	2,754.5
Segment revenue:
Revenue	2,229.0	2,463.6	4,752.1	4,713.7
Revenue Before Reimbursements	884.0	1,060.5	2,013.6	1,959.2
Derivative, Gain (Loss) on Derivative, Net	8.6	4.8	7.0	4.7
Real Estate Revenues, Net	683.1	863.9	1,601.5	1,575.0
Operating expenses:
Compensation, operating and administrative expenses	805.3	913.7	1,815.6	1,724.5
Depreciation and amortization	39.1	26.3	76.5	53.6
Operating Expenses, Excluding Reimbursed Expenses	844.4	940.0	1,892.1	1,778.1
Gross contract vendor and subcontractor costs reimbursement	192.3	191.8	405.1	379.5
Total fee based segment operating expenses	652.1	748.2	1,487.0	1,398.6
General Contractor Cost	(192.3)	(191.8)	(405.1)	(379.5)
Operating Income (Loss)	39.6	120.5	121.5	181.1
Equity in earnings (losses)	2.9	0.4	15.6	0.1
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	42.5	120.9	137.1	181.2
Segment Reconciling Items:
Revenue	2,229.0	2,463.6	4,752.1	4,713.7
Operating Income (Loss)	39.6	120.5	121.5	181.1
Reportable Subsegments [Member] \| EMEA [Member]
Segment Reporting Information [Line Items]
Reimbursement Revenues	168.8	153.7	351.6	318.3
Segment revenue:
Revenue	626.2	818.3	1,382.1	1,541.7
Revenue Before Reimbursements	457.4	664.6	1,030.5	1,223.4
Real Estate Revenues, Net	268.0	379.9	578.5	696.0
Operating expenses:
Compensation, operating and administrative expenses	481.8	654.6	1,066.2	1,231.5
Depreciation and amortization	9.0	11.3	18.2	22.6
Operating Expenses, Excluding Reimbursed Expenses	490.8	665.9	1,084.4	1,254.1
Gross contract vendor and subcontractor costs reimbursement	189.4	284.7	452.0	527.4
Total fee based segment operating expenses	301.4	381.2	632.4	726.7
General Contractor Cost	(189.4)	(284.7)	(452.0)	(527.4)
Operating Income (Loss)	(33.4)	(1.3)	(53.9)	(30.7)
Equity in earnings (losses)	0.0	(1.1)	0.0	(1.0)
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	(33.4)	(2.4)	(53.9)	(31.7)
Segment Reconciling Items:
Revenue	626.2	818.3	1,382.1	1,541.7
Operating Income (Loss)	(33.4)	(1.3)	(53.9)	(30.7)
Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment Reporting Information [Line Items]
Reimbursement Revenues	327.0	359.6	611.9	700.7
Segment revenue:
Revenue	715.3	855.2	1,427.4	1,603.9
Revenue Before Reimbursements	388.3	495.6	815.5	903.2
Real Estate Revenues, Net	198.8	262.9	376.5	461.1
Operating expenses:
Compensation, operating and administrative expenses	362.6	462.6	780.1	863.1
Depreciation and amortization	7.0	6.4	13.6	12.8
Operating Expenses, Excluding Reimbursed Expenses	369.6	469.0	793.7	875.9
Gross contract vendor and subcontractor costs reimbursement	189.5	232.7	439.0	442.1
Total fee based segment operating expenses	180.1	236.3	354.7	433.8
General Contractor Cost	(189.5)	(232.7)	(439.0)	(442.1)
Operating Income (Loss)	18.7	26.6	21.8	27.3
Equity in earnings (losses)	0.5	0.4	(0.2)	0.7
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	19.2	27.0	21.6	28.0
Segment Reconciling Items:
Revenue	715.3	855.2	1,427.4	1,603.9
Operating Income (Loss)	18.7	26.6	21.8	27.3
Investment Management [Member]
Segment Reporting Information [Line Items]
Reimbursement Revenues	1.1	1.9	2.9	3.8
Segment revenue:
Revenue	99.9	129.4	204.8	227.8
Revenue Before Reimbursements	98.8	127.5	201.9	224.0
Real Estate Revenues, Net	95.0	123.3	193.6	217.0
Operating expenses:
Compensation, operating and administrative expenses	82.9	96.0	170.0	178.9
Depreciation and amortization	1.8	1.5	3.6	3.0
Operating Expenses, Excluding Reimbursed Expenses	84.7	97.5	173.6	181.9
Gross contract vendor and subcontractor costs reimbursement	3.8	4.2	8.3	7.0
Total fee based segment operating expenses	80.9	93.3	165.3	174.9
General Contractor Cost	(3.8)	(4.2)	(8.3)	(7.0)
Operating Income (Loss)	14.1	30.0	28.3	42.1
Equity in earnings (losses)	11.3	10.5	(29.0)	15.4
Operating Income (Loss), Including Income (Loss) from Equity Method Investments	25.4	40.5	(0.7)	57.5
Segment Reconciling Items:
Revenue	99.9	129.4	204.8	227.8
Operating Income (Loss)	14.1	30.0	28.3	42.1
Leasing [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	278.1	491.8	697.0	881.6
Segment Reconciling Items:
Revenue	278.1	491.8	697.0	881.6
Leasing [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	46.7	65.9	94.8	118.1
Segment Reconciling Items:
Revenue	46.7	65.9	94.8	118.1
Leasing [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	33.8	66.2	59.2	102.1
Segment Reconciling Items:
Revenue	33.8	66.2	59.2	102.1
Capital Markets [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	140.8	129.8	388.2	229.9
Segment Reconciling Items:
Revenue	140.8	129.8	388.2	229.9
Capital Markets [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	50.0	78.5	123.2	142.5
Segment Reconciling Items:
Revenue	50.0	78.5	123.2	142.5
Capital Markets [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	24.0	48.2	45.7	77.6
Segment Reconciling Items:
Revenue	24.0	48.2	45.7	77.6
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	1,439.5	1,370.9	2,898.3	2,732.9
Segment Reconciling Items:
Revenue	1,439.5	1,370.9	2,898.3	2,732.9
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	320.5	380.6	695.5	749.9
Segment Reconciling Items:
Revenue	320.5	380.6	695.5	749.9
Property & Facility Management [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	515.2	553.4	1,047.2	1,091.2
Segment Reconciling Items:
Revenue	515.2	553.4	1,047.2	1,091.2
Project & Development Services [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	275.3	376.8	581.7	685.5
Segment Reconciling Items:
Revenue	275.3	376.8	581.7	685.5
Project & Development Services [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	164.3	219.2	367.5	399.7
Segment Reconciling Items:
Revenue	164.3	219.2	367.5	399.7
Project & Development Services [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	97.2	137.3	192.0	248.2
Segment Reconciling Items:
Revenue	97.2	137.3	192.0	248.2
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| Americas [Member]
Segment revenue:
Revenue	95.3	94.3	186.9	183.8
Segment Reconciling Items:
Revenue	95.3	94.3	186.9	183.8
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| EMEA [Member]
Segment revenue:
Revenue	44.7	74.1	101.1	131.5
Segment Reconciling Items:
Revenue	44.7	74.1	101.1	131.5
Advisory, Consulting and Other [Member] \| Reportable Subsegments [Member] \| Asia Pacific [Member]
Segment revenue:
Revenue	45.1	50.1	83.3	84.8
Segment Reconciling Items:
Revenue	45.1	50.1	83.3	84.8
Advisory Fees [Member] \| Investment Management [Member]
Segment revenue:
Revenue	80.9	79.5	166.5	157.1
Segment Reconciling Items:
Revenue	80.9	79.5	166.5	157.1
Transaction Fees & Other [Member] \| Investment Management [Member]
Segment revenue:
Revenue	4.8	16.3	18.4	29.5
Segment Reconciling Items:
Revenue	4.8	16.3	18.4	29.5
Incentive Fees [Member] \| Investment Management [Member]
Segment revenue:
Revenue	14.2	33.6	19.9	41.2
Segment Reconciling Items:
Revenue	$ 14.2	$ 33.6	$ 19.9	$ 41.2

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

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

+ References

No definition available.

+ Details

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

- Definition

The aggregate costs related to general contracting services.

+ References

No definition available.

+ Details

Name:	jll_GeneralContractorCost
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

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

+ References

No definition available.

+ Details

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

- Definition

Repayment received or receivable for expenses incurred on behalf of a client or customer.

+ References

No definition available.

+ Details

Name:	jll_ReimbursementRevenues
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://fasb.org/us-gaap/role/ref/legacyRef
-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=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120400017&loc=d3e572229-122910

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

+ Details

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

- 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://fasb.org/us-gaap/role/ref/legacyRef
-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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

+ Details

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

- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(f))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

+ 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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

+ Details

Name:	us-gaap_OperatingIncomeLoss
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

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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:	srt_StatementGeographicalAxis=srt_AmericasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_StatementGeographicalAxis=srt_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:	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: