Securities (Held-to-maturity Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Total investment securities	$ 263,662	$ 279,117
Gross Unrealized Gains	12,282	15,901
Gross Unrealized Losses	(1,145)	(505)
Estimated Fair Value	274,799	294,513
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Total investment securities	0	4,369
Gross Unrealized Gains	0	306
Gross Unrealized Losses	0	0
Estimated Fair Value	0	4,675
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total investment securities	263,662	274,748
Gross Unrealized Gains	12,282	15,595
Gross Unrealized Losses	(1,145)	(505)
Estimated Fair Value	$ 274,799	$ 289,838