Investment Securities (Schedule of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 9,127,302	$ 7,660,319
Gross Unrealized Gains	116,945	59,954
Gross Unrealized Losses	(54,970)	(21,608)
Investment securities available for sale, at fair value	9,189,277	7,698,665
Debt Securities, Available-for-sale and Held-to-maturity	9,137,302	7,670,319
Debt Securities, Held-to-maturity, Fair Value	9,199,277	7,708,665
Investment securities (including securities recorded at fair value of $9,290,883 and $7,759,237)	9,300,883	7,769,237
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,196	70,243
Gross Unrealized Gains	1,714	219
Gross Unrealized Losses	0	(137)
Investment securities available for sale, at fair value	76,910	70,325
U.S. Government agency and sponsored enterprise residential MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,301,188	2,018,853
Gross Unrealized Gains	19,677	9,835
Gross Unrealized Losses	(6,111)	(6,513)
Investment securities available for sale, at fair value	2,314,754	2,022,175
U.S. Government agency and sponsored enterprise commercial MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	532,540	366,787
Gross Unrealized Gains	10,014	4,920
Gross Unrealized Losses	(1,018)	(731)
Investment securities available for sale, at fair value	541,536	370,976
Private label residential mortgage-backed securities and CMOs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,150,571	1,001,337
Gross Unrealized Gains	18,423	11,851
Gross Unrealized Losses	(1,288)	(1,011)
Investment securities available for sale, at fair value	1,167,706	1,012,177
Private label commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,442,409	1,719,228
Gross Unrealized Gains	23,769	6,650
Gross Unrealized Losses	(25,628)	(1,194)
Investment securities available for sale, at fair value	2,440,550	1,724,684
Single family rental real estate-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	755,153	467,459
Gross Unrealized Gains	14,008	4,016
Gross Unrealized Losses	(263)	(1,450)
Investment securities available for sale, at fair value	768,898	470,025
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,158,414	1,204,905
Gross Unrealized Gains	220	322
Gross Unrealized Losses	(16,230)	(7,861)
Investment securities available for sale, at fair value	1,142,404	1,197,366
Non-mortgage asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	245,180	194,171
Gross Unrealized Gains	6,954	1,780
Gross Unrealized Losses	(295)	(1,047)
Investment securities available for sale, at fair value	251,839	194,904
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	222,959	257,528
Gross Unrealized Gains	19,965	15,774
Gross Unrealized Losses	(3)	0
Investment securities available for sale, at fair value	242,921	273,302
SBA securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	243,692	359,808
Gross Unrealized Gains	2,201	4,587
Gross Unrealized Losses	(4,134)	(1,664)
Investment securities available for sale, at fair value	241,759	362,731
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities held to maturity	10,000	10,000
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI	$ 101,606	$ 60,572

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of debt and equity financial instruments classified as either held-to-maturity or available-for-sale.

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Amount of investment in debt security measured at amortized cost (held-to-maturity) and 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 of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Sum of the carrying amounts as of the balance sheet date of all investments.

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