Schedule II—Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful trade receivables
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 4,519	$ 5,570	$ 7,739
Charges to costs and expenses	3,794	1,709	1,259
Recoveries and write offs	(2,647)	(2,760)	(3,428)
Balance at end of period	5,666	4,519	5,570
Allowance for excess and slow moving inventory
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	83,566	45,648	39,247
Charges to costs and expenses	34,155	32,204	5,748
Recoveries and write offs	(9,154)	5,714	653
Balance at end of period	$ 108,567	$ 83,566	$ 45,648