Revenue recognition

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

The Company operates as one operating segment. Therefore, results of its operations are reported on a consolidated basis for purposes of segment reporting, consistent with internal management reporting. The Company's revenues disaggregated by the major sources were as follows:



	Three Months Ended March 31, 2020						Three Months Ended March 31, 2019
	U.S. Government		Non-U.S. Government		Total		U.S. Government		Non-U.S. Government		Total
Product sales, net	$	63.9	$	84.3	$	148.2	$	73.3	$	79.7	$	153.0
Contract development and manufacturing services	—		21.7		21.7		—		15.9		15.9
Contracts and grants	22.0		0.6		22.6		20.4		1.3		21.7
Total revenues	$	85.9	$	106.6	$	192.5	$	93.7	$	96.9	$	190.6

Contract liabilities

When performance obligations are not transferred to a customer at the end of a reporting period, cash received associated with amounts allocated to those performance obligations is reflected as contract liabilities on the consolidated balance sheets and is deferred until control of these performance obligations is transferred to the customer. The following table presents the rollforward of the contract liability balances:




December 31, 2019	$	88.9
Deferral of revenue	6.4
Revenue recognized	(5.9		)
March 31, 2020	$	89.4

Transaction price allocated to remaining performance obligations

As of March 31, 2020, the Company expects future revenues of approximately $555.9 million associated with performance obligations that have not been satisfied. The Company expects to recognize a majority of these revenues within the next 24 months, with the remainder recognized thereafter. However, the amount and timing of revenue recognition for unsatisfied performance obligations can materially change due to timing of funding appropriations from the USG and the overall success of the Company's development activities associated with its PHT product candidates that are then receiving development funding support from the USG under development contracts. In addition, the amount of future revenues associated with unsatisfied performance obligations excludes the value associated with unexercised option periods in the Company's contracts.

Contract assets

The Company considers unbilled accounts receivables and deferred costs associated with revenue generating contracts, which are not included in inventory or property, plant and equipment, as contract assets. As of March 31, 2020 and December 31, 2019, the Company had contract assets associated with deferred costs of $36.3 million and $34.0 million, respectively, which is reflected as a component of prepaid expenses and other current assets on the Company's consolidated balance sheets.

Accounts receivable

Accounts receivable, including unbilled accounts receivable contract assets, consist of the following:



	March 31, 2020		December 31, 2019
Billed, net	$	119.4	$	227.3
Unbilled	43.1		43.4
Total, net	$	162.5	$	270.7

As of March 31, 2020 and December 31, 2019, allowances for doubtful accounts were $0.8 million and de minimis, respectively.