CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Parent	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Deferred Compensation Employee Stock Trust, Net	Employee Stock Trust	Noncontrolling Interest	Total
Increase (Decrease) in Stockholders' Equity
Adoption of accounting standards	$ 1,393				$ 1,393				$ 1,393
Balance at Dec. 31, 2018	1,949,470	$ 936	$ 1,489,816	$ (8,627)	466,737	$ 825	$ (217)	$ 24,423	1,973,893
Balance (in shares) at Dec. 31, 2018		93,610,000					11,000
Increase (Decrease) in Stockholders' Equity
Net income	96,597				96,597			2,971	99,568
Other comprehensive income	16,489			16,489					16,489
Stock-based compensation expense	4,739		4,739						4,739
Common stock issued to board members	281		281						281
Common stock issued to board members (in shares)		15,000
Issuance of common stock related to share-based awards, net	(1,734)	$ 4	(1,738)						(1,734)
Issuance of common stock related to share-based awards, net (in shares)		365,000
Repurchases of common stock	(24,980)	$ (12)	(19,499)		(5,469)				(24,980)
Repurchases of common stock (in shares)		(1,215,000)
Dividends on common stock	(14,983)				(14,983)				(14,983)
Deferred compensation plan	9					(37)	$ 46		9
Deferred compensation plan (in shares)							(2,000)
Net cash distributed to noncontrolling interest								(2,870)	(2,870)
Balance at Jun. 30, 2019	2,027,281	$ 928	1,473,599	7,862	544,275	788	$ (171)	24,524	2,051,805
Balance (in shares) at Jun. 30, 2019		92,775,000					9,000
Balance at Mar. 31, 2019	1,991,527	$ 938	1,491,585	(1,062)	499,452	827	$ (213)	23,604	2,015,131
Balance (in shares) at Mar. 31, 2019		93,821,000					11,000
Increase (Decrease) in Stockholders' Equity
Net income	57,811				57,811			1,980	59,791
Other comprehensive income	8,924			8,924					8,924
Stock-based compensation expense	2,385		2,385						2,385
Common stock issued to board members	141		141						141
Common stock issued to board members (in shares)		7,000
Issuance of common stock related to share-based awards, net	(1,011)	$ 2	(1,013)						(1,011)
Issuance of common stock related to share-based awards, net (in shares)		162,000
Repurchases of common stock	(24,980)	$ (12)	(19,499)		(5,469)				(24,980)
Repurchases of common stock (in shares)		(1,215,000)
Dividends on common stock	(7,519)				(7,519)				(7,519)
Deferred compensation plan	3					(39)	$ 42		3
Deferred compensation plan (in shares)							(2,000)
Net cash distributed to noncontrolling interest								(1,060)	(1,060)
Balance at Jun. 30, 2019	2,027,281	$ 928	1,473,599	7,862	544,275	788	$ (171)	24,524	2,051,805
Balance (in shares) at Jun. 30, 2019		92,775,000					9,000
Increase (Decrease) in Stockholders' Equity
Adoption of accounting standards	(5,691)				(5,691)				(5,691)
Balance at Dec. 31, 2019	2,103,039	$ 906	1,445,233	11,419	644,860	776	$ (155)	25,757	2,128,796
Balance (in shares) at Dec. 31, 2019		90,641,000					8,000
Increase (Decrease) in Stockholders' Equity
Net income	178,112				178,112			10,905	189,017
Other comprehensive income	12,394			12,394					12,394
Stock-based compensation expense	6,759		6,759						6,759
Common stock issued to board members	292		292						292
Common stock issued to board members (in shares)		18,000
Issuance of common stock related to share-based awards, net	(1,024)	$ 3	(1,027)						(1,024)
Issuance of common stock related to share-based awards, net (in shares)		284,000
Repurchases of common stock	(15,249)	$ (7)	(11,571)		(3,671)				$ (15,249)
Repurchases of common stock (in shares)		(721,000)							(720,901)
Dividends on common stock	(16,279)				(16,279)				$ (16,279)
Deferred compensation plan	7					2	$ 5		7
Net cash distributed to noncontrolling interest								(6,889)	(6,889)
Balance at Jun. 30, 2020	2,262,360	$ 902	1,439,686	23,813	797,331	778	$ (150)	29,773	2,292,133
Balance (in shares) at Jun. 30, 2020		90,222,000					8,000
Balance at Mar. 31, 2020	2,136,711	$ 901	1,437,301	20,939	676,946	774	$ (150)	27,022	2,163,733
Balance (in shares) at Mar. 31, 2020		90,108,000					8,000
Increase (Decrease) in Stockholders' Equity
Net income	128,476				128,476			6,939	135,415
Other comprehensive income	2,874			2,874					2,874
Stock-based compensation expense	3,117		3,117						3,117
Common stock issued to board members	146		146						146
Common stock issued to board members (in shares)		8,000
Issuance of common stock related to share-based awards, net	(555)	$ 1	(556)						(555)
Issuance of common stock related to share-based awards, net (in shares)		126,000
Repurchases of common stock	(292)		(322)		30				(292)
Repurchases of common stock (in shares)		(20,000)
Dividends on common stock	(8,121)				(8,121)				(8,121)
Deferred compensation plan	4					4			4
Net cash distributed to noncontrolling interest								(4,188)	(4,188)
Balance at Jun. 30, 2020	$ 2,262,360	$ 902	$ 1,439,686	$ 23,813	$ 797,331	$ 778	$ (150)	$ 29,773	$ 2,292,133
Balance (in shares) at Jun. 30, 2020		90,222,000					8,000