Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of Common Stock Outstanding Roll Forward

The changes in shares of Common and Treasury Stock are as follows:

(in thousands)	Common Shares Issued	Treasury Stock Shares		Common Shares Outstanding
Balance as of December 31, 2016	11,567	645		10,922
Net shares issued for stock awards	—	(11	)	11
Shares issued to Weichai *	2,729	—		2,729
Shares converted from Series B Convertible Preferred Stock *	4,771	—		4,771
Balance as of December 31, 2017	19,067	634		18,433
Net shares issued for Stock awards	—	(205	)	205
Balance as of December 31, 2018	19,067	429		18,638

* See Note 3.Weichai Transactionsfor additional information.