Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Customer receivables, allowances	$ 10,286	$ 8,866
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	280,000,000	140,000,000
Common stock, shares outstanding	117,331,447	119,532,534