Investment Securities, AFS and HTM Securities Gross Unrealized Losses (Details) $ in Thousands	Dec. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (685)	$ (7,843)
Unrealized losses on available for sale securities, 12 months or more	(2,885)	(12,440)
Total unrealized losses on available for sale securities	(3,570)	(20,284)
Fair value of unrealized losses on available for sale securities, less than 12 months	192,720	834,616
Fair value of unrealized losses on available for sale securities, 12 months or more	178,681	748,487
Total fair value of unrealized losses on available for sale securities	$ 371,400	$ 1,583,104
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	27	65
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	16	51
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ 0	$ (2,199)
Unrealized losses on held to maturity securities, 12 months or more	0	(6,164)
Total unrealized losses on held to maturity securities	0	(8,363)
Fair value of unrealized losses on held to maturity securities, less than 12 months	325	292,267
Fair value of unrealized losses on held to maturity securities, 12 months or more	0	367,532
Total fair value of unrealized losses on held to maturity securities	$ 325	$ 659,799
Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months | security	1	67
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer | security	0	36
Obligations of state and political subdivisions (municipal securities)
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months		$ (18)
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		(18)
Fair value of unrealized losses on available for sale securities, less than 12 months		1,225
Fair value of unrealized losses on available for sale securities, 12 months or more		0
Total fair value of unrealized losses on available for sale securities		1,225
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months		(1,105)
Unrealized losses on held to maturity securities, 12 months or more		(13)
Total unrealized losses on held to maturity securities		(1,118)
Fair value of unrealized losses on held to maturity securities, less than 12 months		77,562
Fair value of unrealized losses on held to maturity securities, 12 months or more		2,378
Total fair value of unrealized losses on held to maturity securities		$ 79,940
Obligations of state and political subdivisions (municipal securities) | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security		4
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		52
Obligations of state and political subdivisions (municipal securities) | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security		0
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		6
FFELP asset backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (129)	$ (6,092)
Unrealized losses on available for sale securities, 12 months or more	(2,885)	(393)
Total unrealized losses on available for sale securities	(3,013)	(6,485)
Fair value of unrealized losses on available for sale securities, less than 12 months	9,267	250,780
Fair value of unrealized losses on available for sale securities, 12 months or more	178,681	12,913
Total fair value of unrealized losses on available for sale securities	$ 187,948	$ 263,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	1	19
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	16	2
SBA
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (53)
Unrealized losses on available for sale securities, 12 months or more	0
Total unrealized losses on available for sale securities	(53)
Fair value of unrealized losses on available for sale securities, less than 12 months	8,379
Fair value of unrealized losses on available for sale securities, 12 months or more	0
Total fair value of unrealized losses on available for sale securities	$ 8,379
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	14
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0
Other debt securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ 0	$ 0
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	0	0
Fair value of unrealized losses on available for sale securities, less than 12 months	2,000	2,000
Fair value of unrealized losses on available for sale securities, 12 months or more	0	0
Total fair value of unrealized losses on available for sale securities	$ 2,000	$ 2,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	2	2
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0	0
FNMA/FHLMC [Member] | Residential Related Securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (500)	$ 0
Unrealized losses on available for sale securities, 12 months or more	0	(59)
Total unrealized losses on available for sale securities	(500)	(59)
Fair value of unrealized losses on available for sale securities, less than 12 months	163,002	0
Fair value of unrealized losses on available for sale securities, 12 months or more	0	34,807
Total fair value of unrealized losses on available for sale securities	$ 163,002	$ 34,807
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	7	0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0	4
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months		$ (6)
Unrealized losses on held to maturity securities, 12 months or more		(9)
Total unrealized losses on held to maturity securities		(15)
Fair value of unrealized losses on held to maturity securities, less than 12 months		1,242
Fair value of unrealized losses on held to maturity securities, 12 months or more		833
Total fair value of unrealized losses on held to maturity securities		$ 2,075
FNMA/FHLMC [Member] | Residential Related Securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		1
FNMA/FHLMC [Member] | Residential Related Securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		1
GNMA | Residential Related Securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (3)	$ (924)
Unrealized losses on available for sale securities, 12 months or more	0	(766)
Total unrealized losses on available for sale securities	(3)	(1,689)
Fair value of unrealized losses on available for sale securities, less than 12 months	9,784	322,394
Fair value of unrealized losses on available for sale securities, 12 months or more	0	79,461
Total fair value of unrealized losses on available for sale securities	$ 9,784	$ 401,856
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	2	18
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0	3
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ 0	$ (1,059)
Unrealized losses on held to maturity securities, 12 months or more	0	(49)
Total unrealized losses on held to maturity securities	0	(1,108)
Fair value of unrealized losses on held to maturity securities, less than 12 months	325	187,261
Fair value of unrealized losses on held to maturity securities, 12 months or more	0	6,587
Total fair value of unrealized losses on held to maturity securities	$ 325	$ 193,849
GNMA | Residential Related Securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	1	12
GNMA | Residential Related Securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	0	8
GNMA | Commercial mortgage-related securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ 0	$ (810)
Unrealized losses on available for sale securities, 12 months or more	0	(11,222)
Total unrealized losses on available for sale securities	0	(12,032)
Fair value of unrealized losses on available for sale securities, less than 12 months	287	258,218
Fair value of unrealized losses on available for sale securities, 12 months or more	0	621,307
Total fair value of unrealized losses on available for sale securities	$ 287	$ 879,524
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	1	22
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0	42
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months		$ (29)
Unrealized losses on held to maturity securities, 12 months or more		(6,093)
Total unrealized losses on held to maturity securities		(6,122)
Fair value of unrealized losses on held to maturity securities, less than 12 months		26,202
Fair value of unrealized losses on held to maturity securities, 12 months or more		357,733
Total fair value of unrealized losses on held to maturity securities		$ 383,935
GNMA | Commercial mortgage-related securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		2
GNMA | Commercial mortgage-related securities | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security		21