Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deposits, by Type [Abstract]
Non-interest bearing demand	$ 5,797,600	$ 6,029,600
Interest bearing:
Demand	6,495,200	6,507,800
Savings	7,832,300	7,775,800
Interest bearing	17,218,000	17,293,500
Total deposits	23,015,600	23,323,100
Brokered time deposits	0
Time deposits obtained through Certificate of Deposit Account Registry Service (CDARS)	12,500	26,600
FDIC deposit insurance limit	250,000
Total Time
Due within 3 months or less	1,343,500
Due after 3 months and within 6 months	808,600
Due after 6 months and within 12 months	506,400
Due within 2026	181,300
Due within 2027	37,200
Due within 2028	8,800
Due within 2029 and thereafter	4,700
Total	2,890,500
Interest expense, time deposits, $100,000 or more	32,700	21,500	$ 2,500
Deposit Liability [Line Items]
Due within 3 months or less	1,343,500
Due after 3 months and within 6 months	808,600
Due after 6 months and within 12 months	506,400
Due within 2026	181,300
Due within 2027	37,200
Due within 2028	8,800
Due within 2029 and thereafter	4,700
Total	2,890,500
Time, $250 and Over
Total Time
Due within 3 months or less	418,800
Due after 3 months and within 6 months	219,700
Due after 6 months and within 12 months	122,400
Due within 2026	56,300
Due within 2027	5,100
Due within 2028	1,700
Due within 2029 and thereafter	1,000
Total	825,000	811,600
Deposit Liability [Line Items]
Due within 3 months or less	418,800
Due after 3 months and within 6 months	219,700
Due after 6 months and within 12 months	122,400
Due within 2026	56,300
Due within 2027	5,100
Due within 2028	1,700
Due within 2029 and thereafter	1,000
Total	825,000	811,600
Time, other
Total Time
Due within 3 months or less	924,700
Due after 3 months and within 6 months	588,900
Due after 6 months and within 12 months	384,000
Due within 2026	125,000
Due within 2027	32,100
Due within 2028	7,100
Due within 2029 and thereafter	3,700
Total	2,065,500	2,198,300
Deposit Liability [Line Items]
Due within 3 months or less	924,700
Due after 3 months and within 6 months	588,900
Due after 6 months and within 12 months	384,000
Due within 2026	125,000
Due within 2027	32,100
Due within 2028	7,100
Due within 2029 and thereafter	3,700
Total	$ 2,065,500	$ 2,198,300