Investment Securities (Schedule of the Aggregate Fair Value and Amount by which Amortized Cost Exceeds Fair Value for Investment Securities that are in Unrealized Loss Positions) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 2,976,796	$ 1,922,326
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(65,755)	(9,848)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,308,610	1,205,877
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(35,342)	(11,760)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,285,406	3,128,203
Gross Unrealized Losses	(101,097)	(21,608)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		20,056
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(137)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		20,056
Gross Unrealized Losses	0	(137)
U.S. Government agency and sponsored enterprise residential MBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	604,143	579,076
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(895)	(3,862)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	517,239	243,839
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(4,303)	(2,651)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,121,382	822,915
Gross Unrealized Losses	(5,198)	(6,513)
U.S. Government agency and sponsored enterprise commercial MBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	39,892	99,610
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(108)	(696)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	73,856	6,477
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(818)	(35)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	113,748	106,087
Gross Unrealized Losses	(926)	(731)
Private label residential mortgage-backed securities and CMOs
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	205,524	180,398
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,974)	(838)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	41,636
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(173)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	205,524	222,034
Gross Unrealized Losses	(1,974)	(1,011)
Private label commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,302,037	648,761
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(45,341)	(1,060)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	56,875	76,302
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,457)	(134)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,358,912	725,063
Gross Unrealized Losses	(48,798)	(1,194)
Single family rental real estate-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	184,785	241,915
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,193)	(1,445)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	5,460
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	184,785	247,375
Gross Unrealized Losses	(1,193)	(1,450)
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	591,422	63,310
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(15,873)	(846)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	537,331	682,076
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(22,303)	(7,015)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,128,753	745,386
Gross Unrealized Losses	(38,176)	(7,861)
Non-mortgage asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	13,857	78,964
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(45)	(962)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	13,472	7,883
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(529)	(85)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	27,329	86,847
Gross Unrealized Losses	(574)	(1,047)
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	0	0
SBA securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	35,136	10,236
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(326)	(2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	109,837	142,204
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,932)	(1,662)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	144,973	152,440
Gross Unrealized Losses	$ (4,258)	$ (1,664)