Securities (Held to maturity securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 271,300	$ 279,117
Gross Unrealized Gains	18,492	15,901
Gross Unrealized Losses	(346)	(505)
Estimated Fair Value	289,446	294,513
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	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]
Amortized Cost	271,300	274,748
Gross Unrealized Gains	18,492	15,595
Gross Unrealized Losses	(346)	(505)
Estimated Fair Value	$ 289,446	$ 289,838