CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED BALANCE SHEETS
Allowances for doubtful accounts	$ 4,999	$ 4,701
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	90,965,482	90,952,185
Convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	50,000,000	50,000,000
Convertible preferred stock, shares outstanding	0	0
Treasury stock, shares	24,870,000	24,867,000