Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 6,482,952	$ 6,596,065
Less than 12 months, gross unrealized losses	(428,286)	(96,227)
12 months or longer, fair value	2,963,676	1,523,383
12 months or longer, gross unrealized losses	(273,418)	(43,377)
Total, fair value	9,446,628	8,119,448
Total, gross unrealized losses	(701,704)	(139,604)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	328,920	49,648
Less than 12 months, gross unrealized losses	(14,282)	(379)
12 months or longer, fair value	44,313	47,590
12 months or longer, gross unrealized losses	(5,529)	(2,248)
Total, fair value	373,233	97,238
Total, gross unrealized losses	(19,811)	(2,627)
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	20,691	21,760
Less than 12 months, gross unrealized losses	(1,471)	(387)
12 months or longer, fair value	0	0
12 months or longer, gross unrealized losses	0	0
Total, fair value	20,691	21,760
Total, gross unrealized losses	(1,471)	(387)
Mortgage-backed securities issued by U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	316,662	461,078
Less than 12 months, gross unrealized losses	(19,328)	(5,858)
12 months or longer, fair value	365,096	244,264
12 months or longer, gross unrealized losses	(27,277)	(5,606)
Total, fair value	681,758	705,342
Total, gross unrealized losses	(46,605)	(11,464)
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	5,225,550	5,729,476
Less than 12 months, gross unrealized losses	(365,535)	(82,671)
12 months or longer, fair value	1,966,572	643,758
12 months or longer, gross unrealized losses	(188,380)	(19,409)
Total, fair value	7,192,122	6,373,234
Total, gross unrealized losses	(553,915)	(102,080)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	366,174	187,431
Less than 12 months, gross unrealized losses	(18,823)	(3,981)
12 months or longer, fair value	441,167	504,238
12 months or longer, gross unrealized losses	(35,987)	(12,745)
Total, fair value	807,341	691,669
Total, gross unrealized losses	(54,810)	(16,726)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	224,955	146,672
Less than 12 months, gross unrealized losses	(8,847)	(2,951)
12 months or longer, fair value	146,528	83,533
12 months or longer, gross unrealized losses	(16,245)	(3,369)
Total, fair value	371,483	230,205
Total, gross unrealized losses	$ (25,092)	$ (6,320)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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