Accrued Liabilities an Other Long-term Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities [Abstract]
Salaries and benefits	$ 20,538		$ 20,538	$ 20,745
Incentive compensation	42,913		42,913	40,682
Accrued Professional Fees	15,996		15,996	13,319
Accrued Product Field Action.	5,316		5,316	11,810
Consigned inventory	1,118		1,118	5,210
Third-party Inventory			1,089	4,284
Legal accrual	1,400		1,400	3,538
Accrued sales taxes	2,941		2,941	6,291
Warranties and Returns	1,124		1,124	3,360
Deferred Revenue and Credits, Current	3,814		3,814	3,326
Accrued other taxes	3,213		3,213	2,771
Outside commissions	3,977		3,977	725
Accrued freight	10,953		10,953	5,696
Restructuring Reserve, Current	1,046		1,046	1,290
Contract settlement	12,700	$ 28,900	2,083	0
Accrued research and development expense			1,451	0
Other	9,848		9,848	9,017
Accrued liabilities	$ 128,820		$ 128,820	$ 132,064