Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Condensed Consolidated Balance Sheets
Accounts receivable, allowance for doubtful accounts	$ 5,508	$ 4,975
Accumulated depreciation on property, plant and equipment	$ 180,378	$ 176,995
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	154,866,550	153,638,836
Common stock, shares outstanding	147,508,669	150,851,689
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	3,290,050	4,294,233
Preferred stock, shares outstanding	3,290,050	4,294,233
Common stock held in treasury at cost (in shares)	7,357,881	2,787,147