Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common stock	Retained earnings	Accumulated other comprehensive income (loss)
Beginning balance (in shares) at Dec. 31, 2021		109,312,000
Beginning balance at Dec. 31, 2021	$ 2,390,884	$ 1,685,496	$ 757,921	$ (52,533)
Increase (decrease) in stockholders' equity
Net income for common stock	69,167		69,167
Other comprehensive (loss) income, net of tax benefits	(117,159)			(117,159)
Share-based expenses and other, net (in shares)		119,000
Share-based expenses and other, net	(949)	$ (949)
Common stock dividends	(38,301)		(38,301)
Ending balance (in shares) at Mar. 31, 2022		109,431,000
Ending balance at Mar. 31, 2022	2,303,642	$ 1,684,547	788,787	(169,692)
Beginning balance (in shares) at Dec. 31, 2021		109,312,000
Beginning balance at Dec. 31, 2021	2,390,884	$ 1,685,496	757,921	(52,533)
Increase (decrease) in stockholders' equity
Net income for common stock	183,790
Other comprehensive (loss) income, net of tax benefits	(301,011)
Ending balance (in shares) at Sep. 30, 2022		109,470,000
Ending balance at Sep. 30, 2022	2,162,922	$ 1,689,672	826,794	(353,544)
Beginning balance (in shares) at Mar. 31, 2022		109,431,000
Beginning balance at Mar. 31, 2022	2,303,642	$ 1,684,547	788,787	(169,692)
Increase (decrease) in stockholders' equity
Net income for common stock	52,541		52,541
Other comprehensive (loss) income, net of tax benefits	(87,840)			(87,840)
Share-based expenses and other, net (in shares)		36,000
Share-based expenses and other, net	3,462	$ 3,462
Common stock dividends	(38,301)		(38,301)
Ending balance (in shares) at Jun. 30, 2022		109,467,000
Ending balance at Jun. 30, 2022	2,233,504	$ 1,688,009	803,027	(257,532)
Increase (decrease) in stockholders' equity
Net income for common stock	62,082		62,082
Other comprehensive (loss) income, net of tax benefits	(96,012)			(96,012)
Share-based expenses and other, net (in shares)		3,000
Share-based expenses and other, net	1,663	$ 1,663
Common stock dividends	(38,315)		(38,315)
Ending balance (in shares) at Sep. 30, 2022		109,470,000
Ending balance at Sep. 30, 2022	$ 2,162,922	$ 1,689,672	826,794	(353,544)
Beginning balance (in shares) at Dec. 31, 2022	109,470,795	109,471,000
Beginning balance at Dec. 31, 2022	$ 2,202,499	$ 1,692,697	845,830	(336,028)
Increase (decrease) in stockholders' equity
Net income for common stock	54,721		54,721
Other comprehensive (loss) income, net of tax benefits	20,488			20,488
Share-based expenses and other, net (in shares)		101,000
Share-based expenses and other, net	(307)	$ (307)
Common stock dividends	(39,446)		(39,446)
Ending balance (in shares) at Mar. 31, 2023		109,572,000
Ending balance at Mar. 31, 2023	$ 2,237,955	$ 1,692,390	861,105	(315,540)
Beginning balance (in shares) at Dec. 31, 2022	109,470,795	109,471,000
Beginning balance at Dec. 31, 2022	$ 2,202,499	$ 1,692,697	845,830	(336,028)
Increase (decrease) in stockholders' equity
Net income for common stock	150,449
Other comprehensive (loss) income, net of tax benefits	$ (21,996)
Ending balance (in shares) at Sep. 30, 2023	110,086,035	110,086,000
Ending balance at Sep. 30, 2023	$ 2,224,354	$ 1,704,447	877,931	(358,024)
Beginning balance (in shares) at Mar. 31, 2023		109,572,000
Beginning balance at Mar. 31, 2023	2,237,955	$ 1,692,390	861,105	(315,540)
Increase (decrease) in stockholders' equity
Net income for common stock	54,610		54,610
Other comprehensive (loss) income, net of tax benefits	(7,609)			(7,609)
Share-based expenses and other, net (in shares)		40,000
Share-based expenses and other, net	3,868	$ 3,868
Common stock dividends	(39,447)		(39,447)
Ending balance (in shares) at Jun. 30, 2023		109,612,000
Ending balance at Jun. 30, 2023	2,249,377	$ 1,696,258	876,268	(323,149)
Increase (decrease) in stockholders' equity
Net income for common stock	41,118		41,118
Other comprehensive (loss) income, net of tax benefits	(34,875)			(34,875)
Dividend reinvestment and stock purchase plan (in shares)		474,000
Dividend reinvestment and stock purchase plan	5,827	$ 5,827
Share-based expenses and other, net	2,362	$ 2,362
Common stock dividends	$ (39,455)		(39,455)
Ending balance (in shares) at Sep. 30, 2023	110,086,035	110,086,000
Ending balance at Sep. 30, 2023	$ 2,224,354	$ 1,704,447	$ 877,931	$ (358,024)