Consolidated Statements of Shareholders’ Equity (unaudited) - USD ($) $ in Thousands	Total	Cumulative effect of change in accounting principle for ASU 2022-02	Common Stock	Capital Surplus	Retained Earnings	Retained Earnings Cumulative effect of change in accounting principle for ASU 2022-02	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock
Balance at beginning of period (in shares) at Dec. 31, 2022			72,263,727
Balance at beginning of period at Dec. 31, 2022	$ 3,197,400	$ 1,277	$ 72,264	$ 1,935,211	$ 1,311,258	$ 1,277	$ (46,507)	$ (74,826)
Balance at beginning of period (in shares) at Dec. 31, 2022								2,894,677
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted shares (in shares)			133,430
Issuance of restricted shares	0		$ 134	(134)
Issuance of common shares pursuant to PSU agreements (in shares)			102,973
Issuance of common shares pursuant to PSU agreements	0		$ 103	(103)
Forfeitures of restricted shares (in shares)			(2,083)
Forfeitures of restricted shares	(33)		$ (3)	(30)
Proceeds from exercise of stock options (in shares)			16,000
Proceeds from exercise of stock options	476		$ 16	460
Share-based compensation	7,448			7,448
Purchase of treasury shares (in shares)								480,909
Purchase of treasury shares	(17,077)							$ (17,077)
Net income	203,171				203,171
Dividends on common shares	(31,282)				(31,282)
Other comprehensive income (loss) during the period	(14,311)						(14,311)
Balance at end of period (in shares) at Sep. 30, 2023			72,514,047
Balance at end of period at Sep. 30, 2023	3,347,069		$ 72,514	1,942,852	1,484,424		(60,818)	$ (91,903)
Balance at end of period (in shares) at Sep. 30, 2023								3,375,586
Balance at beginning of period (in shares) at Jun. 30, 2023			72,514,630
Balance at beginning of period at Jun. 30, 2023	3,284,630		$ 72,515	1,939,865	1,414,742		(50,618)	$ (91,874)
Balance at beginning of period (in shares) at Jun. 30, 2023								3,374,847
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted shares (in shares)			1,500
Issuance of restricted shares	0		$ 2	(2)
Forfeitures of restricted shares (in shares)			(2,083)
Forfeitures of restricted shares	(33)		$ (3)	(30)
Share-based compensation	3,019			3,019
Purchase of treasury shares (in shares)								739
Purchase of treasury shares	(29)							$ (29)
Net income	80,115				80,115
Dividends on common shares	(10,433)				(10,433)
Other comprehensive income (loss) during the period	(10,200)						(10,200)
Balance at end of period (in shares) at Sep. 30, 2023			72,514,047
Balance at end of period at Sep. 30, 2023	$ 3,347,069		$ 72,514	1,942,852	1,484,424		(60,818)	$ (91,903)
Balance at end of period (in shares) at Sep. 30, 2023								3,375,586
Balance at beginning of period (in shares) at Dec. 31, 2023	72,516,079		72,516,079
Balance at beginning of period at Dec. 31, 2023	$ 3,426,747		$ 72,516	1,945,385	1,539,957		(35,939)	$ (95,172)
Balance at beginning of period (in shares) at Dec. 31, 2023	3,462,738							3,462,738
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted shares (in shares)			128,391
Issuance of restricted shares	$ 0		$ 129	(129)
Issuance of common shares pursuant to PSU agreements (in shares)			63,301
Issuance of common shares pursuant to PSU agreements	0		$ 63	(63)
Forfeitures of restricted shares (in shares)			(10,116)
Forfeitures of restricted shares	(224)		$ (10)	(214)
Share-based compensation	9,553			9,553
Purchase of treasury shares (in shares)								167,898
Purchase of treasury shares	(7,955)							$ (7,955)
Net income	264,309				264,309
Dividends on common shares	(31,277)				(31,277)
Other comprehensive income (loss) during the period	$ 20,215						20,215
Balance at end of period (in shares) at Sep. 30, 2024	72,697,655		72,697,655
Balance at end of period at Sep. 30, 2024	$ 3,681,368		$ 72,698	1,954,532	1,772,989		(15,724)	$ (103,127)
Balance at end of period (in shares) at Sep. 30, 2024	3,630,636							3,630,636
Balance at beginning of period (in shares) at Jun. 30, 2024			72,697,209
Balance at beginning of period at Jun. 30, 2024	$ 3,566,614		$ 72,697	1,950,846	1,684,218		(38,020)	$ (103,127)
Balance at beginning of period (in shares) at Jun. 30, 2024								3,630,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted shares (in shares)			2,559
Issuance of restricted shares	0		$ 3	(3)
Forfeitures of restricted shares (in shares)			(2,113)
Forfeitures of restricted shares	(43)		$ (2)	(41)
Share-based compensation	3,730			3,730
Purchase of treasury shares	0
Net income	99,212				99,212
Dividends on common shares	(10,441)				(10,441)
Other comprehensive income (loss) during the period	$ 22,296						22,296
Balance at end of period (in shares) at Sep. 30, 2024	72,697,655		72,697,655
Balance at end of period at Sep. 30, 2024	$ 3,681,368		$ 72,698	$ 1,954,532	$ 1,772,989		$ (15,724)	$ (103,127)
Balance at end of period (in shares) at Sep. 30, 2024	3,630,636							3,630,636