Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI, Gain (Loss)	[1]	$ 0	$ (195)		$ 0
Less than 12 Months Fair Value		1,157,774	276,306
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant		(13,446)	(1,598)
12 Months or More Fair Value		521,420	1,873,565
12 Months or More Unrealized Losses		(6,994)	(54,368)
Total Fair Value		1,679,194	2,149,871
Total Unrealized Losses		$ (20,440)	(55,966)
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		243
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		162
Less than 12 Months Fair Value	[2]	$ 1,055,903	114,551
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant	[2]	(12,424)	(750)
12 Months or More Fair Value	[2]	491,539	1,207,020
12 Months or More Unrealized Losses	[2]	(6,798)	(40,096)
Total Fair Value	[2]	1,547,442	1,321,571
Total Unrealized Losses	[2]	$ (19,222)	(40,846)
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		18
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		6
Less than 12 Months Fair Value	[2]	$ 89,508	40,071
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant	[2]	(880)	(222)
12 Months or More Fair Value	[2]	6,799	94,367
12 Months or More Unrealized Losses	[2]	(109)	(2,399)
Total Fair Value	[2]	96,307	134,438
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[2]	$ (989)	(2,621)
State and Municipal Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		24
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		14
Less than 12 Months Fair Value		$ 12,363	106,292
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant		(142)	(581)	[2]
12 Months or More Fair Value		12,587	280,496
12 Months or More Unrealized Losses		(82)	(7,179)
Total Fair Value		24,950	386,788
Total Unrealized Losses		$ (224)	(7,760)
U.S. Government Agency and Government-Sponsored Enterprise Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		3
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		3
Less than 12 Months Fair Value		$ 0	15,392
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant		0	(45)
12 Months or More Fair Value		10,495	291,435
12 Months or More Unrealized Losses		(5)	(4,691)
Total Fair Value		10,495	306,827
Total Unrealized Losses		$ (5)	(4,736)
US Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		0
Less than 12 Months Fair Value			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant			0
12 Months or More Fair Value			247
12 Months or More Unrealized Losses			(3)
Total Fair Value			247
Total Unrealized Losses			$ (3)

[1] Other securities losses, net includes net unrealized loss activity associated with equity securities.

[2] Beginning in 2019, other asset-backed securities were presented separately in this table. Prior period amounts that were previously reported in U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations have been reclassified to conform to current period presentation.