Repurchase Agreements (Details) - Securities Sold under Agreements to Repurchase [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Carrying value of investment securities available for sale pledged as collateral under repurchase agreements	$ 290,700	$ 283,300
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	256,153	235,186
Overnight and Continuous [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	109,581	105,556
Up to 30 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	49,000	1,000
30-90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	717	24,544
Greater Than 90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	96,855	104,086
U.S. Treasury and Government Agencies [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	74,644	28,700
U.S. Treasury and Government Agencies [Member] | Overnight and Continuous [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	19,986	6,790
U.S. Treasury and Government Agencies [Member] | Up to 30 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	22,400	1,000
U.S. Treasury and Government Agencies [Member] | 30-90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	0	6,834
U.S. Treasury and Government Agencies [Member] | Greater Than 90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	32,258	14,076
State and Political Subdivisions [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	71,532	73,764
State and Political Subdivisions [Member] | Overnight and Continuous [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	59,293	59,451
State and Political Subdivisions [Member] | Up to 30 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	2,330	0
State and Political Subdivisions [Member] | 30-90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	508	1,839
State and Political Subdivisions [Member] | Greater Than 90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	9,401	12,474
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	109,977	132,722
U.S. Government Sponsored Agency Mortgage-backed Securities [Member] | Overnight and Continuous [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	30,302	39,315
U.S. Government Sponsored Agency Mortgage-backed Securities [Member] | Up to 30 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	24,270	0
U.S. Government Sponsored Agency Mortgage-backed Securities [Member] | 30-90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	209	15,871
U.S. Government Sponsored Agency Mortgage-backed Securities [Member] | Greater Than 90 Days [Member]
Remaining contractual maturity of securities sold under agreements to repurchase by class of collateral pledged [Abstract]
Repurchase agreements and repurchase-to-maturity transactions	$ 55,196	$ 77,536