Intangible assets

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets

The Company's intangible assets consist of products acquired via business combinations or asset acquisitions. The following tables summarize the Company's intangible assets for the periods ended March 31, 2020 and December 31, 2019:



		March 31, 2020
(in millions)	Estimated Life	Cost		Additions		Accumulated Amortization		Net
Products	9-22 years	$	788.0	$	10.0	$	96.0	$	702.0
Customer relationships	8 years	28.6		—		23.8		4.8
Contract development and manufacturing	8 years	5.5		—		4.2		1.3
Total intangible assets		$	822.1	$	10.0	$	124.0	$	708.1



		December 31, 2019
(in millions)	Estimated Life	Cost		Accumulated Amortization		Net
Products	9-22 years	$	788.0	$	82.2	$	705.8
Customer relationships	8 years	28.6		23.0		$	5.6
Contract development and manufacturing	8 years	5.5		4.0		$	1.5
Total intangible assets		$	822.1	$	109.2	$	712.9

During the three months ended March 31, 2020, the Company achieved a sales milestone that resulted in a $10.0 million obligation related to the Company's asset acquisition of raxibacumab in October 2017. The achievement of the milestone resulted in an increase to intangible assets with a corresponding increase in accounts payable. As of March 31, 2020 there are no remaining contractual obligations for sales milestones related to the raxibacumab acquisition.

During the three months ended March 31, 2020 and 2019, the Company recorded amortization expense for intangible assets of $14.8 million and $14.5 million, respectively. As of March 31, 2020, the weighted average amortization period remaining for intangible assets was 13.3 years.

In-process research and development (IPR&D) assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. There were no changes to the Company's IPR&D assets during the three months ended March 31, 2020.

Goodwill was $266.4 million and $266.6 million for the periods ended March 31, 2020 and December 31, 2019, respectively. The change in the balance during the period was due to foreign currency translation adjustments.