Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Deposits, by Type [Abstract]
Non-interest bearing demand	$ 5,286,800	$ 5,797,600
Interest bearing:
Demand	6,319,700	6,495,200
Savings	7,843,500	7,832,300
Interest bearing	16,801,500	17,218,000
Total deposits	22,088,300	23,015,600
Deposits - branch sale	303,500
Brokered time deposits	0	0
Time deposits obtained through Certificate of Deposit Account Registry Service (CDARS)	13,400	12,500
FDIC deposit insurance limit	250,000
Total Time
Due within 3 months or less	1,197,900
Due after 3 months and within 6 months	873,400
Due after 6 months and within 12 months	459,200
Due within 2027	76,900
Due within 2028	14,000
Due within 2029	7,100
Due within 2030 and thereafter	9,800
Total	2,638,300
Interest expense, time deposits, $100,000 or more	29,700	32,700	$ 21,500
Deposit Liability [Line Items]
Due within 3 months or less	1,197,900
Due after 3 months and within 6 months	873,400
Due after 6 months and within 12 months	459,200
Due within 2027	76,900
Due within 2028	14,000
Due within 2029	7,100
Due within 2030 and thereafter	9,800
Total	2,638,300
Time, $250 and Over
Total Time
Due within 3 months or less	417,700
Due after 3 months and within 6 months	236,900
Due after 6 months and within 12 months	120,900
Due within 2027	14,900
Due within 2028	700
Due within 2029	700
Due within 2030 and thereafter	1,100
Total	792,900	825,000
Deposit Liability [Line Items]
Due within 3 months or less	417,700
Due after 3 months and within 6 months	236,900
Due after 6 months and within 12 months	120,900
Due within 2027	14,900
Due within 2028	700
Due within 2029	700
Due within 2030 and thereafter	1,100
Total	792,900	825,000
Time, other
Total Time
Due within 3 months or less	780,200
Due after 3 months and within 6 months	636,500
Due after 6 months and within 12 months	338,300
Due within 2027	62,000
Due within 2028	13,300
Due within 2029	6,400
Due within 2030 and thereafter	8,700
Total	1,845,400	2,065,500
Deposit Liability [Line Items]
Due within 3 months or less	780,200
Due after 3 months and within 6 months	636,500
Due after 6 months and within 12 months	338,300
Due within 2027	62,000
Due within 2028	13,300
Due within 2029	6,400
Due within 2030 and thereafter	8,700
Total	$ 1,845,400	$ 2,065,500