Borrowings (Tables)

3 Months Ended

Mar. 31, 2019

Borrowings consist of the following (in thousands):

	March 31, 2019			December 31, 2018
Facility Financing Obligation (2019 Notes and Tranche B Notes)
Principal amount	$	11,495		$	11,495
Unamortized debt issuance costs and debt discount		(110	)		(197	)
Net carrying amount	$	11,385		$	11,298
Senior Convertible Notes (2021 Notes)
Principal amount	$	18,690		$	18,690
Unamortized debt issuance costs and debt premium		375			409
Net carrying amount	$	19,065		$	19,099
Note payable to related party - net carrying amount	$	72,036		$	72,089

Total debt - net carrying amount	$	102,486		$	102,486

Schedule of Principal Payment Settlement in Cash or Exchange for Issuance of Shares

Date	2019 notes	Tranche B notes
July 2016	$5.0 million (cash)
April 2017	$5.0 million (equity exchange)	$4.0 million (cash) $1.0 million (equity exchange)
June 2017	$5.0 million (equity exchange)
November 2017	$5.6 million (equity exchange)
January 2018	$3.2 million (equity exchange)
March 2018	$1.3 million (equity exchange)	$5.0 million (equity exchange)
June 2018	$3.0 million (equity exchange)	$3.0 million (equity exchange)
July 2018	$2.0 million (cash) $10.0 million (equity exchange)	$2.0 million (equity exchange)
September 2018	$8.0 million (equity exchange)	$2.5 million (equity exchange)
October 2018	$3.0 million (cash)

Accretion of Debt Issuance Cost and Debt Discount

Accretion of debt issuance cost and debt discount during the three months ended March 31, 2019 and 2018, are as follows (in thousands):

	Three Months Ended March 31,
	2019		2018
Accretion expense - debt issuance cost	$	14	$	6
Accretion expense - debt discount	$	72	$	310

Schedule of Amortization of Premium and Accretion of Debt Issuance Costs

Amortization of the premium and accretion of debt issuance costs related to the 2021 notes for the three months ended March 31, 2019 and 2018 are as follows:

	Three Months Ended March 31,
	2019		2018
Amortization of debt premium	$	36	$	43
Accretion expense - debt issuance cost		2	$	—