Number of joint ventures the company participates under the agreement with co-investment vehicle.

No definition available.

Name:	al_AgreementWithCoInvestmentVehicleNumberOfJointVenturesCompanyParticipated
Namespace Prefix:	al_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of unfunded commitment for equity method investment.

+ References

No definition available.

+ Details

Name:	al_EquityMethodInvestmentUnfundedCommitment
Namespace Prefix:	al_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of aircraft managed by the entity.

+ References

No definition available.

+ Details

Name:	al_NumberOfAircraftManaged
Namespace Prefix:	al_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of aircraft sale transactions.

+ References

No definition available.

+ Details

Name:	al_NumberOfAircraftSaleTransactions
Namespace Prefix:	al_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Information regarding the number of investing funds.

+ References

No definition available.

+ Details

Name:	al_NumberOfInvestmentFunds
Namespace Prefix:	al_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of aircraft sold by the entity during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentNumberOfAircraftSold
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
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_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_CounterpartyNameAxis=al_FinancialInstitutionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=al_ThirdPartyInvestorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=al_ThunderboltAircraftLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=al_BlackbirdCapitalILlcAndBlackbirdCapitalIiLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=al_BlackbirdCapitalIILLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Aircraft under management (Details) $ in Millions	3 Months Ended	9 Months Ended
Aircraft under management (Details) $ in Millions	Sep. 30, 2020 USD ($) aircraft	Sep. 30, 2020 USD ($) item aircraft	Dec. 31, 2019 USD ($)
Investments
Number of aircraft managed		81
Number of platforms		3
Total unfunded commitment \| $	$ 29.1	$ 29.1
Financial Institution
Investments
Number of aircraft managed		4
Third-Party Investors
Investments
Number of aircraft managed		26
Thunderbolt
Investments
Number of aircraft managed		51
Number of investing funds \| item		2
Equity method investment \| $	$ 9.3	$ 9.3	$ 9.9
Number of aircraft sale transactions \| item		3
Non-controlling interest (as a percent)	5.00%	5.00%
Number of aircraft sold or agreed to be sold	1
Blackbird
Investments
Number of aircraft managed		26
Number of investing funds \| item		2
Percentage of equity ownership	9.50%	9.50%
Equity method investment \| $	$ 52.2	$ 52.2	$ 46.5
Blackbird II
Investments
Total unfunded commitment \| $	$ 1,000.0	$ 1,000.0