Stockholders Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 1,270,528	$ 1,203,056
Comprehensive income	(4,456)	25,814
Dividends declared	(8,133)	(8,217)
Common stock repurchases	(15,550)
Employee stock plans	2,571	3,850
Balance	$ 1,244,960	$ 1,224,503
Dividends declared (in dollars per share)	$ 0.16	$ 0.14
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 639	$ 634
Balance (in shares)	63,873	63,367
Employee stock plans		$ 0
Employee stock plans (in shares)	17	51
Balance	$ 639	$ 634
Balance (in shares)	63,890	63,418
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 489,282	$ 470,818
Employee stock plans	2,743	4,039
Balance	492,025	474,857
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ (498,074)	$ 441,668
Balance (in shares)	13,051	12,034
Common stock repurchases	$ (15,550)
Common stock repurchases (in shares)	396
Employee stock plans	$ (84)	$ (80)
Employee stock plans (in shares)	2	1
Balance	$ (513,708)	$ (441,748)
Balance (in shares)	13,449	12,035
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 1,489,176	$ 1,363,772
Comprehensive income	29,733	33,992
Dividends declared	(8,133)	(8,217)
Employee stock plans	(88)	(109)
Balance	1,510,688	1,389,438
Accumulated Other Non-Owner Changes to Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(210,495)	(190,500)
Comprehensive income	(34,189)	(8,178)
Balance	$ (244,684)	$ (198,678)