| Document and Entity Information | Dec. 30, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 30, 2021 |
| Entity Registrant Name | ARCLIGHT CLEAN TRANSITION CORP. II |
| Entity Incorporation, State or Country Code | E9 |
| Entity File Number | 001-39546 |
| Entity Tax Identification Number | 98-1578357 |
| Entity Address, Address Line One | 200 Clarendon Street |
| Entity Address, Address Line Two | 55th Floor |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02116 |
| City Area Code | 617 |
| Local Phone Number | 531-6300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001842279 |
| Units, each consisting of one Class A Ordinary Share, $0.0001 par value, and one-fifth of one redeemable warrant [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Units, each consisting of one Class A Ordinary Share, $0.0001 par value, andone-fifthof one redeemable warrant |
| Trading Symbol | ACTDU |
| Security Exchange Name | NASDAQ |
| Class A Ordinary Shares included as part of the units [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Class A Ordinary Shares included as part of the units |
| Trading Symbol | ACDC |
| Security Exchange Name | NASDAQ |
| Redeemable warrants included as part of the units, each whole warrant exercisable for one Class A Ordinary Share at an exercise price of $11.50 [Member] [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Redeemable warrants included as part of the units, each whole warrant exercisable for one Class A Ordinary Share at an exercise price of $11.50 |
| Trading Symbol | ACTDW |
| Security Exchange Name | NASDAQ |
| Common Class A [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Units, each consisting of one Class A Ordinary Share, $0.0001 par value, and one-fifth of one redeemable warrant |
| Trading Symbol | ACTDU |
| Security Exchange Name | NASDAQ |
