Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Sep. 30, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	5	13
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 21,023	$ 48,258
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (170)	$ (448)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	37	77
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 313,228	$ 617,932
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (5,248)	$ (23,948)
Number of securities in a continuous unrealized loss position total | security	42	90
Fair value of securities in a continuous unrealized loss position total	$ 334,251	$ 666,190
Unrealized losses of securities in a continuous unrealized loss position total	$ (5,418)	$ (24,396)
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	3	0
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 20,331	$ 0
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (169)	$ 0
Number of securities in a continuous unrealized loss position for 12 months or longer | security	4	16
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 50,832	$ 157,032
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (168)	$ (4,467)
Number of securities in a continuous unrealized loss position total | security	7	16
Fair value of securities in a continuous unrealized loss position total	$ 71,163	$ 157,032
Unrealized losses of securities in a continuous unrealized loss position total	$ (337)	$ (4,467)
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	2	10
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 692	$ 47,060
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (1)	$ (439)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	25	51
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 239,550	$ 438,701
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (2,804)	$ (16,178)
Number of securities in a continuous unrealized loss position total | security	27	61
Fair value of securities in a continuous unrealized loss position total	$ 240,242	$ 485,761
Unrealized losses of securities in a continuous unrealized loss position total	$ (2,805)	$ (16,617)
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	$ 12,421	$ 11,772
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (899)	$ (1,535)
Number of securities in a continuous unrealized loss position total | security	5	5
Fair value of securities in a continuous unrealized loss position total	$ 12,421	$ 11,772
Unrealized losses of securities in a continuous unrealized loss position total	$ (899)	$ (1,535)
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	3
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 1,198
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ (9)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	3	5
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 10,425	$ 10,427
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,377)	$ (1,768)
Number of securities in a continuous unrealized loss position total | security	3	8
Fair value of securities in a continuous unrealized loss position total	$ 10,425	$ 11,625
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,377)	$ (1,777)