Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deposits, by Type [Abstract]
Non-interest bearing demand	$ 6,029,600	$ 7,560,000
Interest bearing:
Demand	6,507,800	7,205,900
Savings	7,775,800	8,379,300
Total	811,600	438,000
Time, other	2,198,300	1,490,400
Total interest bearing	17,293,500	17,513,600
Total deposits	23,323,100	25,073,600
Brokered time deposits	0
Time deposits obtained through Certificate of Deposit Account Registry Service (CDARS)	26,600	36,600
Time deposits of $250,000 or more	811,600	438,000
FDIC deposit insurance limit	250,000
Time, $250 and Over
Due within 3 months or less	219,700
Due after 3 months and within 6 months	233,900
Due after 6 months and within 12 months	279,500
Due within 2025	62,800
Due within 2026	9,100
Due within 2027	4,900
Due within 2028 and thereafter	1,700
Total	811,600	438,000
Total Time
Due within 3 months or less	770,400
Due after 3 months and within 6 months	854,000
Due after 6 months and within 12 months	1,024,300
Due within 2025	277,100
Due within 2026	48,200
Due within 2027	28,400
Due within 2028 and thereafter	7,500
Total	3,009,900
Interest expense, time deposits, $100,000 or more	$ 21,500	$ 2,500	$ 900