Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 354,858	$ 1,757,431
Unrealized Loss, Less than 12 months	1,558	27,884
Fair Value, Greater than 12 months	5,708,173	6,377,480
Unrealized Loss, Greater than 12 months	729,822	966,650
Debt Securities, Available-for-sale, Unrealized Loss Position	6,063,031	8,134,911
Unrealized Loss on AFS Debt Securities	731,380	994,534
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	308,226	1,492,875
Unrealized Loss, Less than 12 months	1,294	24,662
Fair Value, Greater than 12 months	572,602	353,129
Unrealized Loss, Greater than 12 months	8,336	17,197
Debt Securities, Available-for-sale, Unrealized Loss Position	880,828	1,846,004
Unrealized Loss on AFS Debt Securities	9,630	41,859
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	0
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	44,746	42,848
Unrealized Loss, Greater than 12 months	10,213	12,576
Debt Securities, Available-for-sale, Unrealized Loss Position	44,746	42,848
Unrealized Loss on AFS Debt Securities	10,213	12,576
State and municipal obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	10,231	14,860
Unrealized Loss, Less than 12 months	173	230
Fair Value, Greater than 12 months	654,343	724,587
Unrealized Loss, Greater than 12 months	52,750	79,685
Debt Securities, Available-for-sale, Unrealized Loss Position	664,574	739,447
Unrealized Loss on AFS Debt Securities	52,923	79,915
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	1,556	3,882
Unrealized Loss, Less than 12 months	5	42
Fair Value, Greater than 12 months	3,235,669	3,409,405
Unrealized Loss, Greater than 12 months	592,554	750,664
Debt Securities, Available-for-sale, Unrealized Loss Position	3,237,225	3,413,287
Unrealized Loss on AFS Debt Securities	592,559	750,706
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	10
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	436,921	564,637
Unrealized Loss, Greater than 12 months	35,079	56,986
Debt Securities, Available-for-sale, Unrealized Loss Position	436,921	564,647
Unrealized Loss on AFS Debt Securities	35,079	56,986
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	34,845	219,414
Unrealized Loss, Less than 12 months	86	2,371
Fair Value, Greater than 12 months	646,644	1,083,938
Unrealized Loss, Greater than 12 months	23,322	36,824
Debt Securities, Available-for-sale, Unrealized Loss Position	681,489	1,303,352
Unrealized Loss on AFS Debt Securities	23,408	39,195
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	36,401	223,306
Unrealized Loss, Less than 12 months	91	2,413
Fair Value, Greater than 12 months	4,319,234	5,057,980
Unrealized Loss, Greater than 12 months	650,955	844,474
Debt Securities, Available-for-sale, Unrealized Loss Position	4,355,635	5,281,286
Unrealized Loss on AFS Debt Securities	651,046	846,887
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	26,390
Unrealized Loss, Less than 12 months	0	579
Fair Value, Greater than 12 months	117,248	198,936
Unrealized Loss, Greater than 12 months	7,568	12,718
Debt Securities, Available-for-sale, Unrealized Loss Position	117,248	225,326
Unrealized Loss on AFS Debt Securities	$ 7,568	$ 13,297