Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Accumulated amortization of intangible assets	$ 22,623	$ 21,133
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, par value (in dollars per share)	$ 0.025	$ 0.025
Common stock, shares authorized (in shares)	140,000,000	140,000,000
Common stock, shares issued (in shares)	84,516,567	83,962,182
Common stock, shares outstanding (in shares)	84,334,531	83,962,182