Accrued Expenses - Warranty Schedule (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Balance as of January 1	$ 16,353	$ 22,468
Warranties provided during the period	5,504	7,106
Settlements made during the period	(10,882)	(13,731)
Changes in liability for pre-existing warranties during the period, including expirations	651	510
Balance as of December 31	$ 11,626	$ 16,353