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	34,944		34,915			34,915	29
Other comprehensive (loss) income	14,716				14,716	14,716
Issuance of 15,799 and 14,971 common shares under stock based compensation awards for the three months ended June 30, 2021 and 2020, respectively and 50,826 and 40,881 common shares under stock based compensation awards for the six months ended June 30, 2021 and 2020, respectively	1,662		882	780		1,662
Cost of 283,759 and 0 shares of common stock acquired for treasury for the three months ended June 30, 2021 and 2020, respectively and 439,216 and 0 shares of common stock acquired for treasury for the six months ended June 30, 2021 and 2020, respectively	0			0		0
Common stock dividend ($0.30 and $0.28 per share for the three months ended June 30, 2021 and 2020, respectively and $0.59 and $0.57 per share for the six months ended June 30, 2021 and 2020, respectively)	(14,575)		(14,575)			(14,575)
Contributions from noncontrolling interests	16,441					0	16,441
Distributions to noncontrolling interests	$ (171)					0	(171)
Issuance of common shares under stock based compensation awards (in shares)	40,881
Common stock acquired for treasury (in shares)	0
Cash dividends (in dollars per share)	$ 0.57
Balance at Jun. 30, 2020	$ 901,653	436,538	484,491	(75,922)	19,888	864,995	36,658
Balance at Mar. 31, 2020	877,302	436,538	472,911	(76,203)	17,651	850,897	26,405
Increase (Decrease) in Shareholders' Equity
Net income	18,526		18,502			18,502	24
Other comprehensive (loss) income	2,237				2,237	2,237
Issuance of 15,799 and 14,971 common shares under stock based compensation awards for the three months ended June 30, 2021 and 2020, respectively and 50,826 and 40,881 common shares under stock based compensation awards for the six months ended June 30, 2021 and 2020, respectively	525		244	281		525
Cost of 283,759 and 0 shares of common stock acquired for treasury for the three months ended June 30, 2021 and 2020, respectively and 439,216 and 0 shares of common stock acquired for treasury for the six months ended June 30, 2021 and 2020, respectively	0			0		0
Common stock dividend ($0.30 and $0.28 per share for the three months ended June 30, 2021 and 2020, respectively and $0.59 and $0.57 per share for the six months ended June 30, 2021 and 2020, respectively)	(7,166)		(7,166)			(7,166)
Contributions from noncontrolling interests	10,301					0	10,301
Distributions to noncontrolling interests	$ (72)					0	(72)
Issuance of common shares under stock based compensation awards (in shares)	14,971
Common stock acquired for treasury (in shares)	0
Cash dividends (in dollars per share)	$ 0.28
Balance at Jun. 30, 2020	$ 901,653	436,538	484,491	(75,922)	19,888	864,995	36,658
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	58,341		58,328			58,328	13
Other comprehensive (loss) income	(10,767)				(10,767)	(10,767)
Issuance of 15,799 and 14,971 common shares under stock based compensation awards for the three months ended June 30, 2021 and 2020, respectively and 50,826 and 40,881 common shares under stock based compensation awards for the six months ended June 30, 2021 and 2020, respectively	2,198		1,271	927		2,198
Cost of 283,759 and 0 shares of common stock acquired for treasury for the three months ended June 30, 2021 and 2020, respectively and 439,216 and 0 shares of common stock acquired for treasury for the six months ended June 30, 2021 and 2020, respectively	(20,398)			(20,398)		(20,398)
Common stock dividend ($0.30 and $0.28 per share for the three months ended June 30, 2021 and 2020, respectively and $0.59 and $0.57 per share for the six months ended June 30, 2021 and 2020, respectively)	(14,980)		(14,980)			(14,980)
Contributions from noncontrolling interests	887					0	887
Distributions to noncontrolling interests	$ (494)					0	(494)
Issuance of common shares under stock based compensation awards (in shares)	50,826
Common stock acquired for treasury (in shares)	439,216
Cash dividends (in dollars per share)	$ 0.59
Balance at Jun. 30, 2021	$ 945,457	436,538	558,795	(101,711)	7,604	901,226	44,231
Balance at Mar. 31, 2021	935,759	436,538	535,737	(88,223)	7,243	891,295	44,464
Increase (Decrease) in Shareholders' Equity
Net income	30,235		30,223			30,223	12
Other comprehensive (loss) income	361				361	361
Issuance of 15,799 and 14,971 common shares under stock based compensation awards for the three months ended June 30, 2021 and 2020, respectively and 50,826 and 40,881 common shares under stock based compensation awards for the six months ended June 30, 2021 and 2020, respectively	716		427	289		716
Cost of 283,759 and 0 shares of common stock acquired for treasury for the three months ended June 30, 2021 and 2020, respectively and 439,216 and 0 shares of common stock acquired for treasury for the six months ended June 30, 2021 and 2020, respectively	(13,777)			(13,777)		(13,777)
Common stock dividend ($0.30 and $0.28 per share for the three months ended June 30, 2021 and 2020, respectively and $0.59 and $0.57 per share for the six months ended June 30, 2021 and 2020, respectively)	(7,592)		(7,592)			(7,592)
Distributions to noncontrolling interests	$ (245)					0	(245)
Issuance of common shares under stock based compensation awards (in shares)	15,799
Common stock acquired for treasury (in shares)	283,759
Cash dividends (in dollars per share)	$ 0.30
Balance at Jun. 30, 2021	$ 945,457	$ 436,538	$ 558,795	$ (101,711)	$ 7,604	$ 901,226	$ 44,231