Investment Securities (Schedule of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	$ 9,475,037	$ 10,328,650
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2,946	2,854
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	646,916	677,061
Debt Securities, Available-for-sale	8,831,067
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss	9,485,037	10,338,650
Debt Securities, Available-for-sale and Held-to-maturity	8,841,067	9,664,443
Investment securities (including securities reported at fair value of $8,876,484 and $9,745,327)	8,886,484	9,755,327
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	119,480	148,956
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	63
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	12,875	13,178
Debt Securities, Available-for-sale	106,605	135,841
U.S. Government agency and sponsored enterprise residential MBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,979,751	2,036,693
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,228	1,334
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	48,521	54,859
Debt Securities, Available-for-sale	1,932,458	1,983,168
U.S. Government agency and sponsored enterprise commercial MBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	572,284	600,517
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	122	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	80,566	75,423
Debt Securities, Available-for-sale	491,840	525,094
Private label residential MBS and CMOs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	2,643,718	2,864,589
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3	54
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	353,396	333,980
Debt Securities, Available-for-sale	2,290,325	2,530,663
Private label commercial MBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	2,351,312	2,645,168
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	767	176
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	95,750	120,990
Debt Securities, Available-for-sale	2,256,329	2,524,354
Single family real estate-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	418,422	502,194
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	24,958	31,753
Debt Securities, Available-for-sale	393,464	470,441
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,059,953	1,166,838
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	575	151
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	12,716	30,526
Debt Securities, Available-for-sale	1,047,812	1,136,463
Non-mortgage asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	108,360	102,194
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	41	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	4,057	6,218
Debt Securities, Available-for-sale	104,344	95,976
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	107,873	122,181
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	695
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	10,638	6,215
Debt Securities, Available-for-sale	97,235	116,661
SBA securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	113,884	139,320
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	210	381
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	3,439	3,919
Debt Securities, Available-for-sale	110,655	135,782
Investment securities held to maturity
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale		9,654,443
Investment securities held to maturity	10,000	10,000
Marketable equity securities
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI	$ 45,417	$ 90,884