Share-Based Employee Compensation - Amounts Recognized for Share-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Cost of employee share-based compensation included in income, before income tax	$ 2,513	$ 3,512	$ 9,478	$ 9,975
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Cost of employee share-based compensation included in income, before income tax	213	253	715	722
Operating expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Cost of employee share-based compensation included in income, before income tax	$ 2,300	$ 3,259	$ 8,763	$ 9,253
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of stock units granted (in shares)	0	0	226,000	307,000
Cost of employee share-based compensation included in income, before income tax	$ 1,337	$ 1,975	$ 4,983	$ 5,575