Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Mar. 31, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	52	22
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 550,438	$ 171,139
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (15,038)	$ (672)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	8	8
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 23,156	$ 22,597
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,345)	$ (1,897)
Number of securities in a continuous unrealized loss position total | security	60	30
Fair value of securities in a continuous unrealized loss position total	$ 573,594	$ 193,736
Unrealized losses of securities in a continuous unrealized loss position total	$ (16,383)	$ (2,569)
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	12	6
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 135,278	$ 63,856
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (4,622)	$ (145)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	0	0
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 0
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 0
Number of securities in a continuous unrealized loss position total | security	12	6
Fair value of securities in a continuous unrealized loss position total	$ 135,278	$ 63,856
Unrealized losses of securities in a continuous unrealized loss position total	$ (4,622)	$ (145)
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	40	16
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 415,160	$ 107,283
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (10,416)	$ (527)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	0	0
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 0
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ 0	$ 0
Number of securities in a continuous unrealized loss position total | security	40	16
Fair value of securities in a continuous unrealized loss position total	$ 415,160	$ 107,283
Unrealized losses of securities in a continuous unrealized loss position total	$ (10,416)	$ (527)
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	$ 12,908	$ 12,669
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (437)	$ (672)
Number of securities in a continuous unrealized loss position total | security	5	5
Fair value of securities in a continuous unrealized loss position total	$ 12,908	$ 12,669
Unrealized losses of securities in a continuous unrealized loss position total	$ (437)	$ (672)
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	$ 10,248	$ 9,928
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (908)	$ (1,225)
Number of securities in a continuous unrealized loss position total | security	3	3
Fair value of securities in a continuous unrealized loss position total	$ 10,248	$ 9,928
Unrealized losses of securities in a continuous unrealized loss position total	$ (908)	$ (1,225)