Share-Based Employee Compensation - Amounts Recognized for Share-Based Compensation (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cost of employee share-based compensation included in income, before income tax	$ 2,933	$ 3,530	$ 4,794	$ 6,965
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cost of employee share-based compensation included in income, before income tax	239	247	395	502
Operating expenses
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cost of employee share-based compensation included in income, before income tax	2,694	3,283	$ 4,399	$ 6,463
Performance Shares
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Number of stock units granted (in shares)			125	265
Cost of employee share-based compensation included in income, before income tax	$ 1,572	$ 1,847	$ 1,817	$ 3,646
Performance Share Units with Total Shareholder Return Conditions
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Number of stock units granted (in shares)			125	149