Investment Securities (Schedule of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 8,597,581	$ 7,660,319
Gross Unrealized Gains	98,447	59,954
Gross Unrealized Losses	(101,097)	(21,608)
Investment securities available for sale, at fair value	8,594,931	7,698,665
Debt Securities, Available-for-sale and Held-to-maturity	8,607,581	7,670,319
Debt Securities, Held-to-maturity, Fair Value	8,604,931	7,708,665
Investment securities (including securities recorded at fair value of $8,683,628 and $7,759,237)	8,693,628	7,769,237
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,217	70,243
Gross Unrealized Gains	1,963	219
Gross Unrealized Losses	0	(137)
Investment securities available for sale, at fair value	77,180	70,325
U.S. Government agency and sponsored enterprise residential MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,371,729	2,018,853
Gross Unrealized Gains	13,309	9,835
Gross Unrealized Losses	(5,198)	(6,513)
Investment securities available for sale, at fair value	2,379,840	2,022,175
U.S. Government agency and sponsored enterprise commercial MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	455,344	366,787
Gross Unrealized Gains	9,859	4,920
Gross Unrealized Losses	(926)	(731)
Investment securities available for sale, at fair value	464,277	370,976
Private label residential mortgage-backed securities and CMOs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,101,390	1,001,337
Gross Unrealized Gains	16,670	11,851
Gross Unrealized Losses	(1,974)	(1,011)
Investment securities available for sale, at fair value	1,116,086	1,012,177
Private label commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,075,683	1,719,228
Gross Unrealized Gains	16,735	6,650
Gross Unrealized Losses	(48,798)	(1,194)
Investment securities available for sale, at fair value	2,043,620	1,724,684
Single family rental real estate-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	608,019	467,459
Gross Unrealized Gains	11,381	4,016
Gross Unrealized Losses	(1,193)	(1,450)
Investment securities available for sale, at fair value	618,207	470,025
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,166,929	1,204,905
Gross Unrealized Gains	0	322
Gross Unrealized Losses	(38,176)	(7,861)
Investment securities available for sale, at fair value	1,128,753	1,197,366
Non-mortgage asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	255,854	194,171
Gross Unrealized Gains	6,251	1,780
Gross Unrealized Losses	(574)	(1,047)
Investment securities available for sale, at fair value	261,531	194,904
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	239,502	257,528
Gross Unrealized Gains	19,993	15,774
Gross Unrealized Losses	0	0
Investment securities available for sale, at fair value	259,495	273,302
SBA securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	247,914	359,808
Gross Unrealized Gains	2,286	4,587
Gross Unrealized Losses	(4,258)	(1,664)
Investment securities available for sale, at fair value	245,942	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	$ 88,697	$ 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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