Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 114,985	$ 62,786	$ 87,399	$ 149,604
Change in debt securities available-for-sale:
Unrealized holding gains (losses) for the period	(304,514)	(35,818)	(733,984)	(109,332)
Reclassification for securities transferred to held-to-maturity	143,310	0	165,473	0
Reclassification adjustment for securities (gains) losses realized in income	85	(692)	(257)	(2,685)
Income tax effect	38,408	9,110	134,643	25,777
Unrealized gains (losses) on available-for-sale securities	(122,711)	(27,400)	(434,125)	(86,240)
Change in securities held-to-maturity:
Adjustment for securities transferred from available-for-sale	(143,310)	0	(165,473)	0
Amortization of unrealized losses on securities transferred     from available-for-sale	3,692	0	4,002	0
Income tax effect	34,146	0	39,272	0
Changes from securities held-to-maturity	(105,472)	0	(122,199)	0
Change in cash flow hedges:
Net unrealized derivative gains (losses) on cash flow hedges	(3,418)	(1,272)	(12,924)	2,776
Reclassification adjustment for (gains) losses realized in net income	(219)	(1,756)	(888)	(1,905)
Income tax effect	894	744	3,394	(214)
Changes from cash flow hedges	(2,743)	(2,284)	(10,418)	657
Change in defined benefit pension plans:
Amortization of net (gains) losses recognized in income	(10)	49	(21)	98
Income tax effect	2	(12)	5	(24)
Changes from defined benefit pension plans	(8)	37	(16)	74
Other comprehensive income (loss), net of tax	(230,934)	(29,647)	(566,758)	(85,509)
Comprehensive income (loss)	$ (115,949)	$ 33,139	$ (479,359)	$ 64,095