Components of asset impairment, restructuring and other special charges for the years ended December 31 are as follows:


	2019		2018		2017
Restructuring charges: ⁽¹⁾
Severance and other costs	$	8.2	$	15.5	$	162.0
Facility exit costs	—		5.7		31.8

Acquisition related charges:
Transaction and integration costs ⁽²⁾	144.7		26.5		90.3

Non-cash and other items:
Asset impairment ⁽³⁾	15.4		81.9		110.6
Asset write-down ⁽⁴⁾	17.2		—		—
Gain on sale of fixed assets ⁽⁵⁾	—		(0.8)		(19.6)

Total expense	$	185.5	$	128.8	$	375.1

⁽¹⁾For the year ended December 31, 2019, these charges primarily relate to a new program that will eliminate certain positions across multiple locations and functions, including exiting R&D operations in Prince Edward Island, Canada, ceasing certain manufacturing operations in Wusi, China, and streamlining operations in Speke, England. We expect to substantially complete these restructuring activities by September 2020.

For the year ended December 31, 2018, these charges primarily relate to a program to streamline international operations, including shifting focus and resources to priority areas. Among other actions, amounts reflect a change from having a physical location to a distribution model in certain countries in connection with the Separation. These activities were substantially complete as of December 31, 2019.

We historically participated in Lilly’s cost-reduction initiatives, which resulted in restructuring charges in the period prior to our IPO. These restructuring charges include severance and other costs associated with the reduction of our workforce, including special termination benefits recognized in 2017 associated with the U.S. voluntary early retirement program offered by Lilly, related to our employees and pension curtailment costs and facility exit costs. We also recorded certain impairment charges related to the activities as described below.

⁽²⁾Transaction costs represent external costs directly related to acquiring businesses and primarily include expenditures for banking, legal, accounting and other similar services. Integration costs represent external, incremental costs directly related to integrating acquired businesses (e.g., expenditures for consulting, system and process integration, and product transfers), as well as stand-up costs related to the implementation of new systems, programs, and processes due to the Separation from Lilly .

•For the year ended December 31, 2019, write-off certain IPR&D and manufacturing assets in the US, Canada and Speke, resulting from the adjustment to fair value of property and equipment and intangible assets that were subject to product rationalization.

•For the year ended December 31, 2018, the decision to dispose of a manufacturing facility in the U.S., the suspension of commercial activities for Imrestor, the write-off of certain idle assets in a U.S. manufacturing facility and product rationalization.

•For the year ended December 31, 2017, intangible asset impairments related to revised projections of fair value due to product rationalization and to a lesser extent competitive pressures.

⁽⁴⁾Asset write-down expenses resulted from the adjustments recorded to write assets classified as held and used and held for sale down to their current fair values. These charges primarily related to fixed assets in Prince Edward Island, Canada; Wusi, China and Indianapolis, Indiana. $11.2 million of Property and equipment, net in Prince Edward Island, Canada and Indianapolis, Indiana are classified as held for sale.

⁽⁵⁾Represents a gain on the disposal of a site that was previously closed as part of the acquisition and integration of Novartis Animal Health beginning on January 1, 2015.