Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Jun. 30, 2017 USD ($) security	Dec. 31, 2016 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	48	47
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 488,558	$ 505,906
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (10,489)	$ (12,726)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	10	10
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 28,258	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,611)	$ (3,115)
Number of securities in a continuous unrealized loss position total | security	58	57
Fair value of securities in a continuous unrealized loss position total	$ 516,816	$ 532,642
Unrealized losses of securities in a continuous unrealized loss position total	$ (12,100)	$ (15,841)
Obligations of U.S. government agencies and U.S. government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	11	10
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 108,930	$ 98,433
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (2,558)	$ (3,050)
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	11	10
Fair value of securities in a continuous unrealized loss position total	$ 108,930	$ 98,433
Unrealized losses of securities in a continuous unrealized loss position total	$ (2,558)	$ (3,050)
Mortgage-backed securities issued by U.S. government-sponsored agencies and U.S. government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	35	35
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 379,226	$ 407,073
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (7,928)	$ (9,671)
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	35	35
Fair value of securities in a continuous unrealized loss position total	$ 379,226	$ 407,073
Unrealized losses of securities in a continuous unrealized loss position total	$ (7,928)	$ (9,671)
Individual name issuer trust preferred debt securities
Schedule of Available-for-sale 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	9	10
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 26,390	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (1,498)	$ (3,115)
Number of securities in a continuous unrealized loss position total | security	9	10
Fair value of securities in a continuous unrealized loss position total	$ 26,390	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position total	$ (1,498)	$ (3,115)
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for less than 12 months | security	2	2
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 402	$ 400
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (3)	$ (5)
Number of securities in a continuous unrealized loss position for 12 months or longer | security	1	0
Fair value of securities in a continuous unrealized loss position for 12 months or longer	$ 1,868	$ 0
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (113)	$ 0
Number of securities in a continuous unrealized loss position total | security	3	2
Fair value of securities in a continuous unrealized loss position total	$ 2,270	$ 400
Unrealized losses of securities in a continuous unrealized loss position total	$ (116)	$ (5)