Stock Compensation Plans (Expense by plan type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 32,843	$ 28,368	$ 28,290
Restricted Stock, Performance Shares, and Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	22,065	21,538	20,145
Long-term incentive plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 10,778	$ 6,830	$ 8,145