Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	13	31
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 48,258	$ 199,567
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (448)	$ (1,416)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	77	40
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 617,932	$ 395,580
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (23,948)	$ (12,119)
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	90	71
Fair value of securities in a continuous unrealized loss position total	$ 666,190	$ 595,147
Unrealized losses of securities in a continuous unrealized loss position total	$ (24,396)	$ (13,535)
Obligations of U.S. government-sponsored enterprises [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	0	8
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ 69,681
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ 0	$ (798)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	16	8
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 157,032	$ 87,923
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (4,467)	$ (3,077)
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	16	16
Fair value of securities in a continuous unrealized loss position total	$ 157,032	$ 157,604
Unrealized losses of securities in a continuous unrealized loss position total	$ (4,467)	$ (3,875)
Mortgage-backed securities issued by U.S. government-sponsored agencies and U.S. government-sponsored enterprises [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	10	20
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 47,060	$ 128,965
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (439)	$ (613)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	51	22
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 438,701	$ 279,693
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (16,178)	$ (7,120)
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	61	42
Fair value of securities in a continuous unrealized loss position total	$ 485,761	$ 408,658
Unrealized losses of securities in a continuous unrealized loss position total	$ (16,617)	$ (7,733)
Individual name issuer trust preferred debt securities [Member]
Schedule of Available for Sale and Held to Maturity Securities [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	7
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 11,772	$ 16,984
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,535)	$ (1,122)
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	5	7
Fair value of securities in a continuous unrealized loss position total	$ 11,772	$ 16,984
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,535)	$ (1,122)
Corporate bonds [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	3	3
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 1,198	$ 921
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (9)	$ (5)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	5	3
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 10,427	$ 10,980
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,768)	$ (800)
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	8	6
Fair value of securities in a continuous unrealized loss position total	$ 11,625	$ 11,901
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,777)	$ (805)