Inventories, Net - Allowance for Excess and Obsolete Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Valuation And Obsolescence [Roll Forward]
Balance at beginning of year	$ 34,402	$ 33,532
Provision	27,341	21,369	$ 32,100
Charges processed	(15,238)	(20,499)
Balance at end of year	$ 46,505	$ 34,402	$ 33,532