Consolidated Statements of Shareholders’ Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss), Net of Tax	Treasury Stock
Balance at beginning of period (in shares) at Dec. 31, 2020		71,753,705
Balance at beginning of period (in shares) at Dec. 31, 2020						2,212,224
Balance at beginning of period at Dec. 31, 2020	$ 2,647,088	$ 71,754	$ 1,913,285	$ 671,510	$ 33,505	$ (42,966)
Issuance of restricted shares (in shares)		99,308
Issuance of restricted shares	599	$ 99	500
Forfeitures of restricted shares (in shares)		(750)
Forfeitures of restricted shares	(20)	$ (1)	(19)
Proceeds from exercise of stock options (in shares)		155,608
Proceeds from exercise of stock options	4,211	$ 156	4,055
Share-based compensation	2,745		2,745
Purchase of treasury shares (in shares)						28,438
Purchase of treasury shares	(1,456)					$ (1,456)
Net income	213,289			213,289
Dividends on common stock shares	(20,971)			(20,971)
Other comprehensive loss during the period	(8,481)				(8,481)
Balance at end of period (in shares) at Jun. 30, 2021		72,007,871
Balance at end of period (in shares) at Jun. 30, 2021						2,240,662
Balance at end of period at Jun. 30, 2021	2,837,004	$ 72,008	1,920,566	863,828	25,024	$ (44,422)
Balance at beginning of period (in shares) at Mar. 31, 2021		71,954,088
Balance at beginning of period (in shares) at Mar. 31, 2021						2,240,662
Balance at beginning of period at Mar. 31, 2021	2,757,596	$ 71,954	1,917,990	785,984	26,090	$ (44,422)
Issuance of restricted shares (in shares)		13,233
Issuance of restricted shares	0	$ 13	(13)
Forfeitures of restricted shares (in shares)		(750)
Forfeitures of restricted shares	(20)	$ (1)	(19)
Proceeds from exercise of stock options (in shares)		41,300
Proceeds from exercise of stock options	1,209	$ 42	1,167
Share-based compensation	1,441		1,441
Net income	88,327			88,327
Dividends on common stock shares	(10,483)			(10,483)
Other comprehensive loss during the period	(1,066)				(1,066)
Balance at end of period (in shares) at Jun. 30, 2021		72,007,871
Balance at end of period (in shares) at Jun. 30, 2021						2,240,662
Balance at end of period at Jun. 30, 2021	2,837,004	$ 72,008	1,920,566	863,828	25,024	$ (44,422)
Balance at beginning of period (in shares) at Dec. 31, 2021		72,017,126
Balance at beginning of period (in shares) at Dec. 31, 2021						2,407,898
Balance at beginning of period at Dec. 31, 2021	2,966,451	$ 72,017	1,924,813	1,006,436	15,590	$ (52,405)
Issuance of restricted shares (in shares)		164,346
Issuance of restricted shares	1,341	$ 164	1,177
Forfeitures of restricted shares (in shares)		(10,751)
Forfeitures of restricted shares	(91)	$ (10)	(81)
Proceeds from exercise of stock options (in shares)		81,135
Proceeds from exercise of stock options	2,324	$ 80	2,244
Share-based compensation	2,935		2,935
Purchase of treasury shares (in shares)						483,497
Purchase of treasury shares	(22,282)					$ (22,282)
Net income	171,764			171,764
Dividends on common stock shares	(20,841)			(20,841)
Other comprehensive loss during the period	(28,225)				(28,225)
Balance at end of period (in shares) at Jun. 30, 2022		72,251,856
Balance at end of period (in shares) at Jun. 30, 2022						2,891,395
Balance at end of period at Jun. 30, 2022	3,073,376	$ 72,251	1,931,088	1,157,359	(12,635)	$ (74,687)
Balance at beginning of period (in shares) at Mar. 31, 2022		72,212,322
Balance at beginning of period (in shares) at Mar. 31, 2022						2,773,238
Balance at beginning of period at Mar. 31, 2022	3,007,159	$ 72,212	1,928,702	1,077,725	(1,841)	$ (69,639)
Issuance of restricted shares (in shares)		18,953
Issuance of restricted shares	0	$ 19	(19)
Forfeitures of restricted shares (in shares)		(10,751)
Forfeitures of restricted shares	(92)	$ (11)	(81)
Proceeds from exercise of stock options (in shares)		31,332
Proceeds from exercise of stock options	880	$ 31	849
Share-based compensation	1,637		1,637
Purchase of treasury shares (in shares)						118,157
Purchase of treasury shares	(5,048)					$ (5,048)
Net income	90,066			90,066
Dividends on common stock shares	(10,432)			(10,432)
Other comprehensive loss during the period	(10,794)				(10,794)
Balance at end of period (in shares) at Jun. 30, 2022		72,251,856
Balance at end of period (in shares) at Jun. 30, 2022						2,891,395
Balance at end of period at Jun. 30, 2022	$ 3,073,376	$ 72,251	$ 1,931,088	$ 1,157,359	$ (12,635)	$ (74,687)