CONSOLIDATED STATEMENT OF CHANGESIN SHAREHOLDERS’ EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exercise of stock options, shares tendered in payment of exercise price (in shares)	19,658	846,789	196,518
Shares paid for tax withholding for share-based compensation	218,587	901,691
Shares surrendered for tax withholding		$ 2,038
Preferred Stock
Underwriting discount and expenses	$ 958	$ 723	$ 1,972
Option
Exercise of stock options, shares tendered in payment of exercise price (in shares)	1,715,019	1,129,195
Warrant
Exercise of stock options, shares tendered in payment of exercise price (in shares)		846,789	196,518