Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	$ 290,918	$ 891,914
Less than 12 Months, Gross Unrealized Losses	(1,752)	(2,468)
12 Months or Longer, Fair Value	0	5,309
12 Months or Longer, Gross Unrealized Losses	0	(38)
Total, Fair Value	290,918	897,223
Total, Gross Unrealized Losses	(1,752)	(2,506)
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	47,091
Less than 12 Months, Gross Unrealized Losses	(56)
12 Months or Longer, Fair Value	0
12 Months or Longer, Gross Unrealized Losses	0
Total, Fair Value	47,091
Total, Gross Unrealized Losses	(56)
Mortgage-backed securities issued by U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	25,126	19,543
Less than 12 Months, Gross Unrealized Losses	(66)	(70)
12 Months or Longer, Fair Value	0	355
12 Months or Longer, Gross Unrealized Losses	0	(2)
Total, Fair Value	25,126	19,898
Total, Gross Unrealized Losses	(66)	(72)
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value		768,040
Less than 12 Months, Gross Unrealized Losses		(2,076)
12 Months or Longer, Fair Value		0
12 Months or Longer, Gross Unrealized Losses		0
Total, Fair Value		768,040
Total, Gross Unrealized Losses		(2,076)
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	142,634	57,670
Less than 12 Months, Gross Unrealized Losses	(146)	(204)
12 Months or Longer, Fair Value	0	0
12 Months or Longer, Gross Unrealized Losses	0	0
Total, Fair Value	142,634	57,670
Total, Gross Unrealized Losses	(146)	(204)
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	33,285
Less than 12 Months, Gross Unrealized Losses	(56)
12 Months or Longer, Fair Value	0
12 Months or Longer, Gross Unrealized Losses	0
Total, Fair Value	33,285
Total, Gross Unrealized Losses	(56)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value		37,156
Less than 12 Months, Gross Unrealized Losses		(116)
12 Months or Longer, Fair Value		4,954
12 Months or Longer, Gross Unrealized Losses		(36)
Total, Fair Value		42,110
Total, Gross Unrealized Losses		(152)
Corporate debt securities and other debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	42,782	9,505
Less than 12 Months, Gross Unrealized Losses	(1,428)	(2)
12 Months or Longer, Fair Value	0	0
12 Months or Longer, Gross Unrealized Losses	0	0
Total, Fair Value	42,782	9,505
Total, Gross Unrealized Losses	$ (1,428)	$ (2)