Overview	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Overview	NOTE A. OVERVIEW Allison Transmission Holdings, Inc. and its subsidiaries ("Allison" or the "Company”) is a global leader in high-performance mobility and work solutions built for the needs of the modern industrial world. Allison operates through two operating and reportable segments: Allison Transmission and Allison Off-Highway Drive & Motion Systems ("Allison Off-Highway"). Headquartered in Indianapolis, Indiana, USA, the Company manufactures solutions which offer industry-leading value propositions across vital sectors such as infrastructure, mining, energy, agriculture, construction, transportation and national security. On January 1, 2026 (the "Closing Date"), the Company completed the acquisition of Dana Incorporated's ("Dana") off-highway business (the "Acquired Off-Highway Business”) for a purchase price of approximately $2,628 million (the "Acquisition"). As a result of the Acquisition, the Company now offers an expanded portfolio of drivetrain, motion and propulsion solutions, providing complementary product breadth and an enhanced ability to support global customers across multiple end markets. The Acquired Off-Highway Business has historically served end markets with demand characteristics that differ from Allison's traditional on-highway markets, contributing to a more diversified portfolio. Following the Acquisition, the Company continues to operate under the Allison name, but its operations are now comprised of two operating and reportable segments: Allison Transmission and Allison Off-Highway. Segment leadership is located globally, reflecting the international nature of the Company's operations and the importance of local market insights, sourcing, production and customer support. All prior period reportable segment information has been reclassified to conform to the current presentation. For additional discussion regarding the Company's segments, including the changes made, see “Note T. Segment Information.” Allison Transmission serves customers through an independent global network of approximately 1,500 independent distributor and dealer locations worldwide and offers more than 200 different transmission models compatible with more than 500 combinations of engine brands, models and ratings, including diesel, gasoline, natural gas and other alternative fuels. In addition, Allison Transmission has developed thousands of proprietary calibrations available for use with its electronic control modules, enabling tailored performance across a broad range of customer applications. Allison Off-Highway provides drivetrain and motion solutions for a wide range of mobile and stationary off-highway equipment. These solutions include optimized drivetrain systems, propulsion components and motion technologies designed for industries such as construction, agriculture, mining, material handling and other industrial applications. The portfolio encompasses systems that manage power conveyance to machines and power work functions, including axles, gearboxes, transmissions and related components, as well as motion systems tailored to customer performance and efficiency requirements across both conventional and electrified powertrains. The global engineering, manufacturing and service footprint of the Acquired Off-Highway Business supports localized responsiveness and technical support for customers in key off-highway end markets. The Company has a global presence serving customers in North America, Asia, Europe, South America, and Africa, and has further expanded its operations in these regions as a result of the Acquisition.

Overview

6 Months Ended

Jun. 30, 2026

NOTE A. OVERVIEW

Allison Transmission Holdings, Inc. and its subsidiaries ("Allison" or the "Company”) is a global leader in high-performance mobility and work solutions built for the needs of the modern industrial world. Allison operates through two operating and reportable segments: Allison Transmission and Allison Off-Highway Drive & Motion Systems ("Allison Off-Highway"). Headquartered in Indianapolis, Indiana, USA, the Company manufactures solutions which offer industry-leading value propositions across vital sectors such as infrastructure, mining, energy, agriculture, construction, transportation and national security.

On January 1, 2026 (the "Closing Date"), the Company completed the acquisition of Dana Incorporated's ("Dana") off-highway business (the "Acquired Off-Highway Business”) for a purchase price of approximately $2,628 million (the "Acquisition"). As a result of the Acquisition, the Company now offers an expanded portfolio of drivetrain, motion and propulsion solutions, providing complementary product breadth and an enhanced ability to support global customers across multiple end markets. The Acquired Off-Highway Business has historically served end markets with demand characteristics that differ from Allison's traditional on-highway markets, contributing to a more diversified portfolio.

Following the Acquisition, the Company continues to operate under the Allison name, but its operations are now comprised of two operating and reportable segments: Allison Transmission and Allison Off-Highway. Segment leadership is located globally, reflecting the international nature of the Company's operations and the importance of local market insights, sourcing, production and customer support. All prior period reportable segment information has been reclassified to conform to the current presentation. For additional discussion regarding the Company's segments, including the changes made, see “Note T. Segment Information.”

Allison Transmission serves customers through an independent global network of approximately 1,500 independent distributor and dealer locations worldwide and offers more than 200 different transmission models compatible with more than 500 combinations of engine brands, models and ratings, including diesel, gasoline, natural gas and other alternative fuels. In addition, Allison Transmission has developed thousands of proprietary calibrations available for use with its electronic control modules, enabling tailored performance across a broad range of customer applications.

Allison Off-Highway provides drivetrain and motion solutions for a wide range of mobile and stationary off-highway equipment. These solutions include optimized drivetrain systems, propulsion components and motion technologies designed for industries such as construction, agriculture, mining, material handling and other industrial applications. The portfolio encompasses systems that manage power conveyance to machines and power work functions, including axles, gearboxes, transmissions and related components, as well as motion systems tailored to customer performance and efficiency requirements across both conventional and electrified powertrains. The global engineering, manufacturing and service footprint of the Acquired Off-Highway Business supports localized responsiveness and technical support for customers in key off-highway end markets.

The Company has a global presence serving customers in North America, Asia, Europe, South America, and Africa, and has further expanded its operations in these regions as a result of the Acquisition.