Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 1,344,060	$ 2,523,310
Less than 12 months, gross unrealized losses	(50,422)	(173,930)
12 months or longer, fair value	8,026,163	6,989,855
12 months or longer, gross unrealized losses	(1,395,745)	(1,423,854)
Total, fair value	9,370,223	9,513,165
Total, gross unrealized losses	(1,446,167)	(1,597,784)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	94,424	139,737
Less than 12 months, gross unrealized losses	(2,869)	(6,789)
12 months or longer, fair value	361,097	307,582
12 months or longer, gross unrealized losses	(33,633)	(37,351)
Total, fair value	455,521	447,319
Total, gross unrealized losses	(36,502)	(44,140)
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	28,845	28,938
Less than 12 months, gross unrealized losses	(1,146)	(1,053)
12 months or longer, fair value	19,841	19,603
12 months or longer, gross unrealized losses	(2,307)	(2,560)
Total, fair value	48,686	48,541
Total, gross unrealized losses	(3,453)	(3,613)
Mortgage-backed securities issued by U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	119,866	187,655
Less than 12 months, gross unrealized losses	(1,730)	(5,952)
12 months or longer, fair value	538,765	521,395
12 months or longer, gross unrealized losses	(99,969)	(107,516)
Total, fair value	658,631	709,050
Total, gross unrealized losses	(101,699)	(113,468)
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	699,851	1,473,348
Less than 12 months, gross unrealized losses	(31,589)	(120,135)
12 months or longer, fair value	6,038,186	5,365,233
12 months or longer, gross unrealized losses	(1,105,532)	(1,130,105)
Total, fair value	6,738,037	6,838,581
Total, gross unrealized losses	(1,137,121)	(1,250,240)
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	11,850	119,649
Less than 12 months, gross unrealized losses	(335)	(10,311)
12 months or longer, fair value	636,709	535,478
12 months or longer, gross unrealized losses	(104,983)	(104,060)
Total, fair value	648,559	655,127
Total, gross unrealized losses	(105,318)	(114,371)
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	380,458	565,382
Less than 12 months, gross unrealized losses	(12,586)	(29,383)
12 months or longer, fair value	431,565	240,564
12 months or longer, gross unrealized losses	(49,321)	(42,262)
Total, fair value	812,023	805,946
Total, gross unrealized losses	(61,907)	(71,645)
Corporate debt securities and other debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	8,766	8,601
Less than 12 months, gross unrealized losses	(167)	(307)
12 months or longer, fair value	0	0
12 months or longer, gross unrealized losses	0	0
Total, fair value	8,766	8,601
Total, gross unrealized losses	$ (167)	$ (307)