Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowances	$ 25,824	$ 20,477
Accumulated depreciation	$ 83,382	$ 80,956
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock authorized (shares)	4,000,000	4,000,000
Preferred stock outstanding (shares)	0	0
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	250,000,000	250,000,000
Common stock issued (shares)	104,000,000	103,000,000
Common stock outstanding (shares)	69,600,000	73,300,000
Treasury stock (shares)	34,400,000	29,700,000

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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