Commitments (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) item	Dec. 31, 2017
Commitments [Line Items]
Contract period for inventory purchase		2 years
Period for options to extend contract period		4 years
Period of options exercised		1 year
Purchase commitment amount purchased	$ 40,878,000
Minimum [Member]
Commitments [Line Items]
Purchase commitment quantity | item	150,000
Purchase commitment	$ 11,104,000
Maximum [Member]
Commitments [Line Items]
Purchase commitment quantity | item	245,900
Purchase commitment	$ 51,028,000