CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Preferred stock, convertible, shares authorized (in shares)	5,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	47,318,000	45,161,000
Common stock, shares outstanding (in shares)	46,485,000	44,510,000
Treasury stock, shares (in shares)	833,000	651,000
Series A-2 Preferred Stock
Preferred stock, convertible, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, convertible, stated value	$ 7,500	$ 7,500
Preferred stock, convertible, shares authorized (in shares)	7,500	7,500
Preferred stock, convertible, shares issued (in shares)	32	32
Preferred stock, convertible, shares outstanding (in shares)	32	32
Preferred stock, convertible, liquidation value	$ 237,000	$ 237,000
Series B Preferred Stock
Preferred stock, convertible, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, convertible, stated value	$ 1,000	$ 1,000
Preferred stock, convertible, shares authorized (in shares)	2,800	2,800
Preferred stock, convertible, shares issued (in shares)	375	450
Preferred stock, convertible, shares outstanding (in shares)	375	450
Preferred stock, convertible, liquidation value	$ 375,000	$ 375,000
Series C Preferred Stock
Preferred stock, convertible, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, convertible, stated value	$ 1,000	$ 1,000
Preferred stock, convertible, shares authorized (in shares)	1,750	1,750
Preferred stock, convertible, shares issued (in shares)	1,275	0
Preferred stock, convertible, shares outstanding (in shares)	1,275	0
Preferred stock, convertible, liquidation value	$ 1,275,000	$ 0