Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets
Accounts receivable, allowance for doubtful accounts		$ 4,975	$ 4,359
Accumulated depreciation on property, plant and equipment		$ 176,995	$ 154,060
Common stock, par value (in dollars per share)		$ 0.0001	$ 0.0001	$ 0.0001
Common stock shares authorized		1,600,000,000	1,600,000,000
Common stock, shares issued		153,638,836	152,692,140
Common stock, shares outstanding		150,851,689	150,142,955
Common stock, shares returned	4,570,734
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		4,294,233	4,569,233
Preferred stock, shares outstanding		4,294,233	4,569,233
Common stock held in treasury at cost (in shares)		2,787,147	2,549,185