Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts receivable, less allowances of $0 and $537	$ 0	$ 537
Preferred stock, par value (in USD per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	14,399,000	14,399,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	71,379,000	71,268,000
Common stock, shares outstanding (in shares)	30,806,000	30,701,000
Treasury stock, shares of common held at cost (in shares)	40,573,000	40,567,000