ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Accumulated Other Comprehensive Loss
Beginning balance	$ 2,697,177	$ 2,347,952	$ 2,466,667	$ 2,304,983
Other comprehensive loss before reclassifications			(97,802)	32,815
Amounts reclassified from accumulated other comprehensive loss			0	6
Period change	(94,344)	34,111	(97,802)	32,821
Ending balance	2,636,381	2,412,402	2,636,381	2,412,402
Total
Accumulated Other Comprehensive Loss
Beginning balance	(133,593)	(189,975)	(130,135)	(188,685)
Period change	(94,344)	34,111	(97,802)	32,821
Ending balance	(227,937)	(155,864)	(227,937)	(155,864)
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Loss
Beginning balance			(131,902)	(188,412)
Other comprehensive loss before reclassifications			(97,802)	32,815
Amounts reclassified from accumulated other comprehensive loss			0	6
Period change			(97,802)	32,821
Ending balance	(229,704)	(155,591)	(229,704)	(155,591)
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Loss
Beginning balance			1,767	(273)
Other comprehensive loss before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive loss			0	0
Period change			0	0
Ending balance	$ 1,767	$ (273)	$ 1,767	$ (273)

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details