Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Amortized cost and fair value of securities held to maturity
Amortized Cost	$ 412,075	$ 317,766
Gross Unrealized Gains	7,911	16,976
Gross Unrealized Losses	(11,410)	(267)
Fair Value	408,576	334,475
Obligations of other U.S. Government agencies and corporations
Amortized cost and fair value of securities held to maturity
Amortized Cost	125,061	90,045
Gross Unrealized Gains	14	116
Gross Unrealized Losses	(8,727)	(232)
Fair Value	116,348	89,929
Obligations of states and political subdivisions
Amortized cost and fair value of securities held to maturity
Amortized Cost	287,014	227,721
Gross Unrealized Gains	7,897	16,860
Gross Unrealized Losses	(2,683)	(35)
Fair Value	$ 292,228	$ 244,546