Revenues

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

The following table presents a summary of total revenues (in thousands):



	Three Months Ended March 31,
	2020		2019
Xyrem	$	407,875	$	368,317
Erwinaze/Erwinase	37,732		60,899
Defitelio/defibrotide	47,432		41,500
Vyxeos	32,720		28,943
Sunosi	1,924		—
Other	2,522		3,672
Product sales, net	530,205		503,331
Royalties and contract revenues	4,521		4,855
Total revenues	$	534,726	$	508,186

The following table presents a summary of total revenues attributed to geographic sources (in thousands):



	Three Months Ended March 31,
	2020		2019
United States	$	478,483	$	462,862
Europe	41,556		35,401
All other	14,687		9,923
Total revenues	$	534,726	$	508,186

The following table presents a summary of the percentage of total revenues from customers that represented more than 10% of our total revenues:



	Three Months Ended March 31,
	2020		2019
ESSDS	76	%	72	%
McKesson	13	%	18	%

Financing and payment

Our payment terms vary by the type and location of our customer but payment is generally required in a term ranging from 30 to 45 days.

Contract Liabilities - Deferred Revenue

The deferred revenue balance as of March 31, 2020 primarily related to deferred upfront fees received from Nippon Shinyaku Co., Ltd., or Nippon Shinyaku, in connection with two license, development and commercialization agreements granting Nippon Shinyaku exclusive rights to develop and commercialize each of Defitelio and Vyxeos in Japan. We recognized contract revenues of $1.2 million during the three months ended March 31, 2020 relating to these upfront payments.

The deferred revenue balances are being recognized over an average of four years representing the period over which we expect to perform our research and developments obligations under each agreement.

The following table presents a reconciliation of our beginning and ending balances in contract liabilities from contracts with customers for the three months ended March 31, 2020 (in thousands):



	Contract Liabilities
Balance as of December 31, 2019	$	9,581
Amount recognized within royalties and contract revenues	(1,180		)
Balance as of March 31, 2020	$	8,401