CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Accounts receivable, reserves	$ 4,266	$ 4,702
Common stock, par value (in USD per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	105,478,000	105,087,000
Common stock, shares outstanding (in shares)	86,103,000	86,100,000
Deferred stock units, outstanding (in shares)	144,000	162,000
Treasury stock, shares (in shares)	19,375,000	18,988,000