Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Sep. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	20	7
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 192,313	$ 61,514
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (1,039)	$ (192)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	8	34
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 22,239	$ 289,468
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (2,247)	$ (4,708)
Number of securities in a continuous unrealized loss position total | security	28	41
Fair value of securities in a continuous unrealized loss position total	$ 214,552	$ 350,982
Unrealized losses of securities in a continuous unrealized loss position total	$ (3,286)	$ (4,900)
Obligations of U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	4	3
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 43,704	$ 20,364
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (296)	$ (136)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	0	3
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 49,902
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ (97)
Number of securities in a continuous unrealized loss position total | security	4	6
Fair value of securities in a continuous unrealized loss position total	$ 43,704	$ 70,266
Unrealized losses of securities in a continuous unrealized loss position total	$ (296)	$ (233)
Mortgage-backed securities issued by U.S. government-sponsored agencies and U.S. government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	16	4
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 148,609	$ 41,150
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (743)	$ (56)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	0	23
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 216,804
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ (2,908)
Number of securities in a continuous unrealized loss position total | security	16	27
Fair value of securities in a continuous unrealized loss position total	$ 148,609	$ 257,954
Unrealized losses of securities in a continuous unrealized loss position total	$ (743)	$ (2,964)
Individual name issuer trust preferred debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	0	0
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 0
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 0
Number of securities in a continuous unrealized loss position for 12 months or longer | security	5	5
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 12,363	$ 12,579
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (973)	$ (745)
Number of securities in a continuous unrealized loss position total | security	5	5
Fair value of securities in a continuous unrealized loss position total	$ 12,363	$ 12,579
Unrealized losses of securities in a continuous unrealized loss position total	$ (973)	$ (745)
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	0	0
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 0
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 0
Number of securities in a continuous unrealized loss position for 12 months or longer | security	3	3
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 9,876	$ 10,183
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,274)	$ (958)
Number of securities in a continuous unrealized loss position total | security	3	3
Fair value of securities in a continuous unrealized loss position total	$ 9,876	$ 10,183
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,274)	$ (958)