CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended							6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Cumulative dividends declared per common share	$ 0.44	$ 0.44	$ 0.41		$ 0.41	$ 0.41	$ 0.41	$ 0.88	$ 0.82
NET INCOME	$ 47,965	$ 43,963	$ 49,927	$ 49,884	$ 54,382	$ 46,855		$ 91,928	$ 101,237
Other comprehensive loss, net of income tax	(101,824)	(154,275)	(14,755)	(23,312)	25,285	(56,103)
Accrual of dividends on common stock	(15,378)	(15,066)	(14,200)	(14,354)	(14,459)	(14,589)
Amortization of stock-based compensation related to restricted stock grants, net of shares surrendered	2,247	(1,169)	2,236	2,339	(259)	1,714
Repurchase of common stock	(10,960)			(16,649)	(14,555)	(25,324)
Total shareholders’ equity	$ 1,485,830	$ 1,563,780	$ 1,690,327	$ 1,667,119	$ 1,669,211	$ 1,618,817		$ 1,485,830	$ 1,669,211	$ 1,666,264
Cumulative dividends declared per common share	$ 0.44	$ 0.44	$ 0.41		$ 0.41	$ 0.41	$ 0.41	$ 0.88	$ 0.82
Common Stock [Member]
Amortization of stock-based compensation related to restricted stock grants, net of shares surrendered (in shares)	18,546	120,152	641	1,103	65,545	76,143
Stock Repurchased and Retired During Period, Shares	(200,000)			(300,000)	(250,000)	(500,000)
Shares, Outstanding	34,191,330	34,372,784	34,252,632	34,251,991	34,550,888	34,735,343		34,191,330	34,550,888	35,159,200
Common Stock and Paid in Capital [Member]
Amortization of stock-based compensation related to restricted stock grants, net of shares surrendered	$ 2,247	$ (1,169)	$ 2,236	$ 2,339	$ (259)	$ 1,714
Repurchase of common stock	(10,960)			(16,649)	(14,555)	(25,324)
Total shareholders’ equity	1,289,499	1,298,212	1,299,381	1,297,145	1,311,455	1,326,269		$ 1,289,499	$ 1,311,455	$ 1,349,879
Retained Earnings [Member]
NET INCOME	47,965	43,963	49,927	49,884	54,382	46,855
Accrual of dividends on common stock	(15,378)	(15,066)	(14,200)	(14,354)	(14,459)	(14,589)
Total shareholders’ equity	452,246	419,659	390,762	355,035	319,505	279,582		452,246	319,505	247,316
Accumulated Other Comprehensive Income (Loss) [Member]
Other comprehensive loss, net of income tax	(101,824)	(154,275)	(14,755)	(23,312)	25,285	(56,103)
Total shareholders’ equity	$ (255,915)	$ (154,091)	$ 184	$ 14,939	$ 38,251	$ 12,966		$ (255,915)	$ 38,251	$ 69,069