Error Correction (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation								$ 11,799,000	$ 7,862,000	$ 6,313,000
Employee profit sharing bonus plan								$ 7,400,000	6,200,000	8,400,000
Corrections | Cost of Sales
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		0	300,000
Corrections | Selling, General and Administrative Expenses
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Share-based compensation	700,000	600,000	3,000,000.0	(600,000)	(600,000)	100,000	1,600,000		500,000	100,000
Employee profit sharing bonus plan	$ 100,000	$ 100,000	$ 400,000	$ 100,000	$ 100,000	$ 100,000	$ 200,000		$ 100,000	$ 100,000