Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable, reserves	$ 4,896	$ 5,128
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	102,831,000	102,237,000
Deferred stock units, outstanding	231,000	240,000
Treasury stock, shares	13,271,000	12,242,000