Investment Securities (Schedule of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	$ 10,028,525	$ 10,328,650
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	5,304	2,854
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	578,999	677,061
Debt Securities, Available-for-sale	9,454,830
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss	10,038,525	10,338,650
Debt Securities, Available-for-sale and Held-to-maturity	9,464,830	9,664,443
Investment securities (including securities reported at fair value of $9,523,599 and $9,745,327)	9,533,599	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	129,140	148,956
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	290	63
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	11,047	13,178
Debt Securities, Available-for-sale	118,383	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	2,028,070	2,036,693
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,528	1,334
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	49,065	54,859
Debt Securities, Available-for-sale	1,980,533	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	584,464	600,517
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	140	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	66,222	75,423
Debt Securities, Available-for-sale	518,382	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	2,825,107	2,864,589
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	807	54
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	300,432	333,980
Debt Securities, Available-for-sale	2,525,482	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	2,533,319	2,645,168
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	887	176
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	99,387	120,990
Debt Securities, Available-for-sale	2,434,819	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	468,225	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	19,724	31,753
Debt Securities, Available-for-sale	448,501	470,441
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,126,532	1,166,838
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	416	151
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	20,870	30,526
Debt Securities, Available-for-sale	1,106,078	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	98,812	102,194
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	4,713	6,218
Debt Securities, Available-for-sale	94,099	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	106,897	122,181
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	926	695
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	3,873	6,215
Debt Securities, Available-for-sale	103,950	116,661
SBA securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	127,959	139,320
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	310	381
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	3,666	3,919
Debt Securities, Available-for-sale	124,603	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	$ 68,769	$ 90,884

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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