Disclosures About Fair Value of Assets and Liabilities - Fair Value Measurements of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	$ 636,785	$ 658,400
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	631,281	652,468
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	5,504	5,932
Fair Value, Measurements, Recurring | Interest rate swap liability | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap liability	13,656	8,070
Fair Value, Measurements, Recurring | Interest rate swap liability | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap liability	13,656	8,070
Fair Value, Measurements, Recurring | U.S. Government-sponsored agency securities | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	103	104
Fair Value, Measurements, Recurring | U.S. Government-sponsored agency securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	103	104
Fair Value, Measurements, Recurring | State and municipal | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	324,651	300,014
Fair Value, Measurements, Recurring | State and municipal | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	5,469	5,897
Fair Value, Measurements, Recurring | State and municipal | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	330,120	305,911
Fair Value, Measurements, Recurring | U.S. Government-sponsored mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	302,586	346,266
Fair Value, Measurements, Recurring | U.S. Government-sponsored mortgage-backed securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	302,586	346,266
Fair Value, Measurements, Recurring | Certificates of deposit | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities		2,176
Fair Value, Measurements, Recurring | Certificates of deposit | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities		2,176
Fair Value, Measurements, Recurring | Corporate obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	31	31
Fair Value, Measurements, Recurring | Corporate obligations | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	31	31
Fair Value, Measurements, Recurring | Equity securities | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,941	3,908
Fair Value, Measurements, Recurring | Equity securities | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	4	4
Fair Value, Measurements, Recurring | Equity securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,945	3,912
Fair Value, Measurements, Recurring | Interest rate swap asset | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate derivatives	8,635	4,938
Fair Value, Measurements, Recurring | Interest rate swap asset | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate derivatives	8,635	4,938
Fair Value, Measurements, Recurring | Interest rate cap | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate derivatives	12	36
Fair Value, Measurements, Recurring | Interest rate cap | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate derivatives	$ 12	$ 36