Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Mar. 31, 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	0	13
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 48,258
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ (448)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	73	77
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 573,191	$ 617,932
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (12,538)	$ (23,948)
Number of securities in a continuous unrealized loss position total | security	73	90
Fair value of securities in a continuous unrealized loss position total	$ 573,191	$ 666,190
Unrealized losses of securities in a continuous unrealized loss position total	$ (12,538)	$ (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	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	14	16
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 139,573	$ 157,032
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,927)	$ (4,467)
Number of securities in a continuous unrealized loss position total | security	14	16
Fair value of securities in a continuous unrealized loss position total	$ 139,573	$ 157,032
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,927)	$ (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	0	10
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 47,060
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ (439)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	47	51
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 409,374	$ 438,701
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (8,347)	$ (16,178)
Number of securities in a continuous unrealized loss position total | security	47	61
Fair value of securities in a continuous unrealized loss position total	$ 409,374	$ 485,761
Unrealized losses of securities in a continuous unrealized loss position total	$ (8,347)	$ (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	$ 12,370	$ 11,772
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (941)	$ (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	$ 12,370	$ 11,772
Unrealized losses of securities in a continuous unrealized loss position total	$ (941)	$ (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	7	5
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 11,874	$ 10,427
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,323)	$ (1,768)
Number of securities in a continuous unrealized loss position total | security	7	8
Fair value of securities in a continuous unrealized loss position total	$ 11,874	$ 11,625
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,323)	$ (1,777)