Stockholders Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 1,382,677	$ 1,270,528
Comprehensive income	(25,520)	(4,456)
Dividends declared	(8,104)	(8,133)
Employee stock plans	2,314	2,571
Balance	$ 1,351,367	$ 1,244,960
Dividends declared (in dollars per share)	$ 0.16	$ 0.16
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 642	$ 639
Balance (in shares)	64,171	63,873
Employee stock plans		$ 0
Employee stock plans (in shares)	12	17
Balance	$ 642	$ 639
Balance (in shares)	64,183	63,890
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 501,531	$ 489,282
Employee stock plans	2,406	2,743
Balance	503,937	492,025
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ (516,992)	$ (498,074)
Balance (in shares)	13,530	13,051
Employee stock plans	$ (68)	$ (84)
Employee stock plans (in shares)	1	2
Balance	$ (517,060)	$ (513,708)
Balance (in shares)	13,531	13,449
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 1,519,811	$ 1,489,176
Comprehensive income	19,382	29,733
Dividends declared	(8,104)	(8,133)
Employee stock plans	(24)	(88)
Balance	1,531,065	1,510,688
Accumulated Other Non-Owner Changes to Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(122,315)	(210,495)
Comprehensive income	(44,902)	(34,189)
Balance	$ (167,217)	$ (244,684)