Investment Securities, AFS and HTM Securities Gross Unrealized Losses (Details) $ in Thousands	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months	$ (7,843)	$ (5,262)
Unrealized losses on available for sale securities, 12 months or more	(12,440)	(93,347)
Total unrealized losses on available for sale securities	(20,284)	(98,610)
Fair value of unrealized losses on available for sale securities, less than 12 months	834,616	613,612
Fair value of unrealized losses on available for sale securities, 12 months or more	748,487	3,009,417
Total fair value of unrealized losses on available for sale securities	$ 1,583,104	$ 3,623,028
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	65	41
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	51	190
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (2,199)	$ (4,053)
Unrealized losses on held to maturity securities, 12 months or more	(6,164)	(43,780)
Total unrealized losses on held to maturity securities	(8,363)	(47,835)
Fair value of unrealized losses on held to maturity securities, less than 12 months	292,267	390,929
Fair value of unrealized losses on held to maturity securities, 12 months or more	367,532	1,349,063
Total fair value of unrealized losses on held to maturity securities	$ 659,799	$ 1,739,992
Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months | security	67	298
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer | security	36	865
U.S. Treasury securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months		$ 0
Unrealized losses on available for sale securities, 12 months or more		(1)
Total unrealized losses on available for sale securities		(1)
Fair value of unrealized losses on available for sale securities, less than 12 months		0
Fair value of unrealized losses on available for sale securities, 12 months or more		999
Total fair value of unrealized losses on available for sale securities		$ 999
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		0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security		1
Obligations of state and political subdivisions (municipal securities)(a)
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
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
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]
Unrealized losses on held to maturity securities, less than 12 months	$ (1,105)	$ (2,860)
Unrealized losses on held to maturity securities, 12 months or more	(13)	(12,419)
Total unrealized losses on held to maturity securities	(1,118)	(15,279)
Fair value of unrealized losses on held to maturity securities, less than 12 months	77,562	313,212
Fair value of unrealized losses on held to maturity securities, 12 months or more	2,378	509,374
Total fair value of unrealized losses on held to maturity securities	$ 79,940	$ 822,586
Obligations of state and political subdivisions (municipal securities)(a) | 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	52	272
Obligations of state and political subdivisions (municipal securities)(a) | 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	6	752
Private-label
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Unrealized losses on available for sale securities, less than 12 months		$ (4)
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		(4)
Fair value of unrealized losses on available for sale securities, less than 12 months		1,003
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		$ 1,003
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
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security		0
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	$ (6,092)	$ (698)
Unrealized losses on available for sale securities, 12 months or more	(393)	0
Total unrealized losses on available for sale securities	(6,485)	(698)
Fair value of unrealized losses on available for sale securities, less than 12 months	250,780	142,432
Fair value of unrealized losses on available for sale securities, 12 months or more	12,913	0
Total fair value of unrealized losses on available for sale securities	$ 263,693	$ 142,432
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	19	13
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	2	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
Unrealized losses on available for sale securities, 12 months or more	0
Total unrealized losses on available for sale securities	0
Fair value of unrealized losses on available for sale securities, less than 12 months	2,000
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	$ 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
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	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	$ 0	$ (31)
Unrealized losses on available for sale securities, 12 months or more	(59)	(3,479)
Total unrealized losses on available for sale securities	(59)	(3,510)
Fair value of unrealized losses on available for sale securities, less than 12 months	0	17,993
Fair value of unrealized losses on available for sale securities, 12 months or more	34,807	189,405
Total fair value of unrealized losses on available for sale securities	$ 34,807	$ 207,398
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	0	15
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	4	17
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (6)	$ (780)
Unrealized losses on held to maturity securities, 12 months or more	(9)	(1,015)
Total unrealized losses on held to maturity securities	(15)	(1,795)
Fair value of unrealized losses on held to maturity securities, less than 12 months	1,242	57,896
Fair value of unrealized losses on held to maturity securities, 12 months or more	833	28,888
Total fair value of unrealized losses on held to maturity securities	$ 2,075	$ 86,784
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	13
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	22
GNMA [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	$ (924)	$ (4,529)
Unrealized losses on available for sale securities, 12 months or more	(766)	(37,355)
Total unrealized losses on available for sale securities	(1,689)	(41,885)
Fair value of unrealized losses on available for sale securities, less than 12 months	322,394	452,183
Fair value of unrealized losses on available for sale securities, 12 months or more	79,461	1,598,159
Total fair value of unrealized losses on available for sale securities	$ 401,856	$ 2,050,342
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	18	12
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	3	79
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (1,059)	$ (414)
Unrealized losses on held to maturity securities, 12 months or more	(49)	(7,767)
Total unrealized losses on held to maturity securities	(1,108)	(8,181)
Fair value of unrealized losses on held to maturity securities, less than 12 months	187,261	19,822
Fair value of unrealized losses on held to maturity securities, 12 months or more	6,587	320,387
Total fair value of unrealized losses on held to maturity securities	$ 193,849	$ 340,209
GNMA [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	12	13
GNMA [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	8	66
GNMA [Member] | 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	$ (810)	$ 0
Unrealized losses on available for sale securities, 12 months or more	(11,222)	(52,512)
Total unrealized losses on available for sale securities	(12,032)	(52,512)
Fair value of unrealized losses on available for sale securities, less than 12 months	258,218	0
Fair value of unrealized losses on available for sale securities, 12 months or more	621,307	1,220,854
Total fair value of unrealized losses on available for sale securities	$ 879,524	$ 1,220,854
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	22	0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	42	93
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (29)	$ 0
Unrealized losses on held to maturity securities, 12 months or more	(6,093)	(22,579)
Total unrealized losses on held to maturity securities	(6,122)	(22,579)
Fair value of unrealized losses on held to maturity securities, less than 12 months	26,202	0
Fair value of unrealized losses on held to maturity securities, 12 months or more	357,733	490,414
Total fair value of unrealized losses on held to maturity securities	$ 383,935	$ 490,414
GNMA [Member] | 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	0
GNMA [Member] | 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	25