Equity - Changes in Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Beginning Balance	$ 1,375,401	$ 1,167,341	$ 1,320,914	$ 1,242,366
Net income (loss)	31,073	27,342	103,305	(8,724)
Amounts reported in other comprehensive income (loss)	(18,780)	34,271	(28,119)	3,046
Dividends	(7,424)	(7,048)	(21,548)	(20,735)
Acquisition of noncontrolling interest				(1,047)
Distributions to noncontrolling affiliate shareholders				(751)
Share issuance and equity-based compensation plans	3,426	4,525	9,144	13,187
Ending Balance	1,383,696	1,226,431	1,383,696	1,226,431
Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				(911)
Adjusted Balance [Member]
Beginning Balance				1,241,455
Common Stock [Member]
Beginning Balance	17,878	17,800	17,851	17,735
Net income (loss)	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends	0	0	0	0
Acquisition of noncontrolling interest				0
Distributions to noncontrolling affiliate shareholders				0
Share issuance and equity-based compensation plans	11	31	38	96
Ending Balance	17,889	17,831	17,889	17,831
Common Stock [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				0
Common Stock [Member] | Adjusted Balance [Member]
Beginning Balance				17,735
Capital in Excess of Par Value [Member]
Beginning Balance	910,862	896,108	905,171	888,218
Net income (loss)	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends	0	0	0	0
Acquisition of noncontrolling interest				(707)
Distributions to noncontrolling affiliate shareholders				0
Share issuance and equity-based compensation plans	3,415	4,494	9,106	13,091
Ending Balance	914,277	900,602	914,277	900,602
Capital in Excess of Par Value [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				0
Capital in Excess of Par Value [Member] | Adjusted Balance [Member]
Beginning Balance				888,218
Retained Earnings [Member]
Beginning Balance	482,001	362,265	423,940	412,979
Net income (loss)	31,058	27,304	103,243	(8,812)
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends	(7,424)	(7,048)	(21,548)	(20,735)
Acquisition of noncontrolling interest				0
Distributions to noncontrolling affiliate shareholders				0
Share issuance and equity-based compensation plans	0	0	0	0
Ending Balance	505,635	382,521	505,635	382,521
Retained Earnings [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				(911)
Retained Earnings [Member] | Adjusted Balance [Member]
Beginning Balance				412,068
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(35,943)	(109,264)	(26,598)	(78,170)
Net income (loss)	0	0	0	0
Amounts reported in other comprehensive income (loss)	(18,780)	34,254	(28,125)	3,160
Dividends	0	0	0	0
Acquisition of noncontrolling interest				0
Distributions to noncontrolling affiliate shareholders				0
Share issuance and equity-based compensation plans	0	0	0	0
Ending Balance	(54,723)	(75,010)	(54,723)	(75,010)
Accumulated Other Comprehensive Income (Loss) [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				0
Accumulated Other Comprehensive Income (Loss) [Member] | Adjusted Balance [Member]
Beginning Balance				(78,170)
Noncontrolling Interest [Member]
Beginning Balance	603	432	550	1,604
Net income (loss)	15	38	62	88
Amounts reported in other comprehensive income (loss)	0	17	6	(114)
Dividends	0	0	0	0
Acquisition of noncontrolling interest				(340)
Distributions to noncontrolling affiliate shareholders				(751)
Share issuance and equity-based compensation plans	0	0	0	0
Ending Balance	$ 618	$ 487	$ 618	487
Noncontrolling Interest [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning Balance				0
Noncontrolling Interest [Member] | Adjusted Balance [Member]
Beginning Balance				$ 1,604