Share-Based Compensation and Capital Stock - Pre-Tax Stock-Based Compensation Expenses And Associated Income Tax Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-Based Compensation and Capital Stock [Line Items]
Share-based compensation expense	$ 2,265	$ 4,043	$ (487)	$ 7,761
Income tax benefits	(539)	(966)	116	(1,854)
Stock options
Share-Based Compensation and Capital Stock [Line Items]
Share-based compensation expense	490	535	981	1,126
Restricted stock
Share-Based Compensation and Capital Stock [Line Items]
Share-based compensation expense	2,099	2,170	4,043	4,146
Performance Vested Restricted Stock Units
Share-Based Compensation and Capital Stock [Line Items]
Share-based compensation expense	$ (324)	$ 1,338	$ (5,511)	$ 2,489