Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Capital Surplus	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss), Net of Tax	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting for leases		$ (276)				$ (276)
Balance at beginning of period (in shares) at Dec. 31, 2018			49,014,925					(1,514,984)
Balance at beginning of period at Dec. 31, 2018	$ 1,456,347		$ 49,015	$ 1,051,584	$ 377,135		$ (4,826)	$ (16,561)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			22,181,522
Issuance of common stock	869,294		$ 22,182	847,112
Issuance of restricted shares (in shares)			147,574
Issuance of restricted shares	915		$ 147	768
Forfeitures of restricted shares (in shares)			(41,295)
Forfeitures of restricted shares	(559)		$ (41)	(518)
Exercise of stock options (in shares)			197,103
Exercise of stock options	5,139		$ 197	4,942
Share-based compensation	3,220			3,220
Purchase of treasury shares (in shares)								481,012
Purchase of treasury shares	(18,410)							$ (18,410)
Net income	161,441				161,441
Dividends on common shares	(30,350)				(30,350)
Other comprehensive income (loss) during the period	22,821						22,821
Balance at end of period (in shares) at Dec. 31, 2019			71,499,829					(1,995,996)
Balance at end of period at Dec. 31, 2019	$ 2,469,582		$ 71,500	1,907,108	507,950		17,995	$ (34,971)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-13
Cumulative effect of change in accounting for leases		$ (56,704)				$ (56,704)
Issuance of restricted shares (in shares)			164,476
Issuance of restricted shares	$ 289		$ 164	125
Forfeitures of restricted shares (in shares)			(12,250)
Forfeitures of restricted shares	(221)		$ (12)	(209)
Exercise of stock options (in shares)			101,650
Exercise of stock options	2,262		$ 102	2,160
Share-based compensation	4,101			4,101
Purchase of treasury shares (in shares)								216,228
Purchase of treasury shares	(7,995)							$ (7,995)
Net income	261,988				261,988
Dividends on common shares	(41,724)				(41,724)
Other comprehensive income (loss) during the period	15,510						15,510
Balance at end of period (in shares) at Dec. 31, 2020			71,753,705					(2,212,224)
Balance at end of period at Dec. 31, 2020	2,647,088		$ 71,754	1,913,285	671,510		33,505	$ (42,966)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted shares (in shares)			99,308
Issuance of restricted shares	599		$ 99	500
Forfeitures of restricted shares (in shares)			(2,695)
Forfeitures of restricted shares	(53)		$ (3)	(50)
Exercise of stock options (in shares)			166,808
Exercise of stock options	4,532		$ 167	4,365
Share-based compensation	6,713			6,713
Purchase of treasury shares (in shares)								195,674
Purchase of treasury shares	(9,439)							$ (9,439)
Net income	376,913				376,913
Dividends on common shares	(41,987)				(41,987)
Other comprehensive income (loss) during the period	(17,915)						(17,915)
Balance at end of period (in shares) at Dec. 31, 2021			72,017,126					(2,407,898)
Balance at end of period at Dec. 31, 2021	$ 2,966,451		$ 72,017	$ 1,924,813	$ 1,006,436		$ 15,590	$ (52,405)