CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable, reserve for doubtful accounts	$ 13,594	$ 12,600
Property, plant and equipment, accumulated depreciation	135,922	119,435
Finite-Lived Intangible Assets, Accumulated Amortization	$ 195,835	$ 168,369
Preferred stock, par value (in usd per share)	$ 10	$ 10
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, shares authorized	95,000,000	95,000,000
Common stock, shares issued	62,675,917	62,445,315
Treasury stock, shares	6,763,041	4,905,549