CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Cost of Common Stock in Treasury	Accumulated Other Comprehensive Income (Loss), Net	Total Shareholders' Equity	Noncontrolling Interests
Balance at Dec. 31, 2019	$ 848,636	$ 436,538	$ 463,269	$ (76,702)	$ 5,172	$ 828,277	$ 20,359
Increase (Decrease) in Shareholders' Equity
Net income	54,998		54,973			54,973	25
Other comprehensive (loss) income	14,486				14,486	14,486
Issuance of 6,936 and 3,289 common shares under stock based compensation awards for the three months ended September 30, 2021 and 2020, respectively and 57,762 and 44,170 common shares under stock based compensation awards for the nine months ended September 30, 2021 and 2020, respectively	1,775		934	841		1,775
Cost of 210,130 and 0 shares of common stock acquired for treasury for the three months ended September 30, 2021 and 2020, respectively and 649,346 and 0 shares of common stock acquired for treasury for the nine months ended September 30, 2021 and 2020, respectively	0			0		0
Common stock dividend ($0.31 and $0.28 per share for the three months ended September 30, 2021 and 2020, respectively and $0.90 and $0.85 per share for the nine months ended September 30, 2021 and 2020, respectively)	(21,757)		(21,757)			(21,757)
Contributions from noncontrolling interests	17,369					0	17,369
Distributions to noncontrolling interests	$ (492)					0	(492)
Issuance of common shares under stock based compensation awards (in shares)	44,170
Common stock acquired for treasury (in shares)	0
Cash dividends (in dollars per share)	$ 0.85
Balance at Sep. 30, 2020	$ 915,015	436,538	497,419	(75,861)	19,658	877,754	37,261
Balance at Jun. 30, 2020	901,653	436,538	484,491	(75,922)	19,888	864,995	36,658
Increase (Decrease) in Shareholders' Equity
Net income	20,054		20,058			20,058	(4)
Other comprehensive (loss) income	(230)				(230)	(230)
Issuance of 6,936 and 3,289 common shares under stock based compensation awards for the three months ended September 30, 2021 and 2020, respectively and 57,762 and 44,170 common shares under stock based compensation awards for the nine months ended September 30, 2021 and 2020, respectively	113		52	61		113
Cost of 210,130 and 0 shares of common stock acquired for treasury for the three months ended September 30, 2021 and 2020, respectively and 649,346 and 0 shares of common stock acquired for treasury for the nine months ended September 30, 2021 and 2020, respectively	0			0		0
Common stock dividend ($0.31 and $0.28 per share for the three months ended September 30, 2021 and 2020, respectively and $0.90 and $0.85 per share for the nine months ended September 30, 2021 and 2020, respectively)	(7,182)		(7,182)			(7,182)
Contributions from noncontrolling interests	928					0	928
Distributions to noncontrolling interests	$ (321)					0	(321)
Issuance of common shares under stock based compensation awards (in shares)	3,289
Common stock acquired for treasury (in shares)	0
Cash dividends (in dollars per share)	$ 0.28
Balance at Sep. 30, 2020	$ 915,015	436,538	497,419	(75,861)	19,658	877,754	37,261
Balance at Dec. 31, 2020	930,670	436,538	514,176	(82,240)	18,371	886,845	43,825
Increase (Decrease) in Shareholders' Equity
Net income	90,822		90,811			90,811	11
Other comprehensive (loss) income	(15,954)				(15,954)	(15,954)
Issuance of 6,936 and 3,289 common shares under stock based compensation awards for the three months ended September 30, 2021 and 2020, respectively and 57,762 and 44,170 common shares under stock based compensation awards for the nine months ended September 30, 2021 and 2020, respectively	2,453		1,399	1,054		2,453
Cost of 210,130 and 0 shares of common stock acquired for treasury for the three months ended September 30, 2021 and 2020, respectively and 649,346 and 0 shares of common stock acquired for treasury for the nine months ended September 30, 2021 and 2020, respectively	(30,067)			(30,067)		(30,067)
Common stock dividend ($0.31 and $0.28 per share for the three months ended September 30, 2021 and 2020, respectively and $0.90 and $0.85 per share for the nine months ended September 30, 2021 and 2020, respectively)	(22,755)		(22,755)			(22,755)
Contributions from noncontrolling interests	2,005					0	2,005
Distributions to noncontrolling interests	$ (777)					0	(777)
Issuance of common shares under stock based compensation awards (in shares)	57,762
Common stock acquired for treasury (in shares)	649,346
Cash dividends (in dollars per share)	$ 0.90
Balance at Sep. 30, 2021	$ 956,397	436,538	583,631	(111,253)	2,417	911,333	45,064
Balance at Jun. 30, 2021	945,457	436,538	558,795	(101,711)	7,604	901,226	44,231
Increase (Decrease) in Shareholders' Equity
Net income	32,481		32,483			32,483	(2)
Other comprehensive (loss) income	(5,187)				(5,187)	(5,187)
Issuance of 6,936 and 3,289 common shares under stock based compensation awards for the three months ended September 30, 2021 and 2020, respectively and 57,762 and 44,170 common shares under stock based compensation awards for the nine months ended September 30, 2021 and 2020, respectively	255		128	127		255
Cost of 210,130 and 0 shares of common stock acquired for treasury for the three months ended September 30, 2021 and 2020, respectively and 649,346 and 0 shares of common stock acquired for treasury for the nine months ended September 30, 2021 and 2020, respectively	(9,669)			(9,669)		(9,669)
Common stock dividend ($0.31 and $0.28 per share for the three months ended September 30, 2021 and 2020, respectively and $0.90 and $0.85 per share for the nine months ended September 30, 2021 and 2020, respectively)	(7,775)		(7,775)			(7,775)
Contributions from noncontrolling interests	1,118					0	1,118
Distributions to noncontrolling interests	$ (283)					0	(283)
Issuance of common shares under stock based compensation awards (in shares)	6,936
Common stock acquired for treasury (in shares)	210,130
Cash dividends (in dollars per share)	$ 0.31
Balance at Sep. 30, 2021	$ 956,397	$ 436,538	$ 583,631	$ (111,253)	$ 2,417	$ 911,333	$ 45,064