Securities (Held to maturity securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 283,258	$ 284,587
Gross Unrealized Gains	11,659	13,793
Gross Unrealized Losses	(2,353)	(1,612)
Estimated Fair Value	292,564	296,768
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5,555	5,734
Gross Unrealized Gains	266	217
Gross Unrealized Losses	(816)	(667)
Estimated Fair Value	5,005	5,284
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	277,703	278,853
Gross Unrealized Gains	11,393	13,576
Gross Unrealized Losses	(1,537)	(945)
Estimated Fair Value	$ 287,559	$ 291,484