Securities (Securities in a Continuous Unrealized Loss Position) (Details) $ in Thousands	Mar. 31, 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	47	47
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 488,720	$ 505,906
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (12,189)	$ (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	$ 26,937	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (2,923)	$ (3,115)
Number of securities in a continuous unrealized loss position total | security	57	57
Fair value of securities in a continuous unrealized loss position total	$ 515,657	$ 532,642
Unrealized losses of securities in a continuous unrealized loss position total	$ (15,112)	$ (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	10	10
Fair value of securities in a continuous unrealized loss position for less than 12 months	$ 98,249	$ 98,433
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (3,240)	$ (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	10	10
Fair value of securities in a continuous unrealized loss position total	$ 98,249	$ 98,433
Unrealized losses of securities in a continuous unrealized loss position total	$ (3,240)	$ (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	$ 390,070	$ 407,073
Unrealized losses of securities in a continuous unrealized loss position for less than 12 months	$ (8,946)	$ (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	$ 390,070	$ 407,073
Unrealized losses of securities in a continuous unrealized loss position total	$ (8,946)	$ (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	$ 25,137	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (2,743)	$ (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	$ 25,137	$ 26,736
Unrealized losses of securities in a continuous unrealized loss position total	$ (2,743)	$ (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	$ 401	$ 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	$ 1,800	$ 0
Unrealized losses of securities in a continuous unrealized loss position for 12 months or longer	$ (180)	$ 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	$ 2,201	$ 400
Unrealized losses of securities in a continuous unrealized loss position total	$ (183)	$ (5)