Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	$ 8,605	$ 8,992
Available-for-sale securities, at fair value	1,449,926	1,402,236
Other borrowings, fair value	10,920	10,961
Obligations of U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	7,240	7,404
Available-for-sale securities, at fair value	583,304	557,820
Residential Mortgage-backed securities U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	1,365	1,588
Available-for-sale securities, at fair value	684,564	659,120
Obligations of U.S. states and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	73,573	71,510
Residential Mortgage-backed securities U.S. Government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	105,106	109,926
Residential Mortgage-backed securities Non-U.S. Government agencies or sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	262	271
U.S. corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	2,162	2,162
Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	955	1,427
Recurring [Member] | Fair Value [Member] | Other borrowings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other borrowings, fair value	10,920	10,961
Recurring [Member] | Fair Value [Member] | Obligations of U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	7,240	7,404
Available-for-sale securities, at fair value	583,304	557,820
Recurring [Member] | Fair Value [Member] | Residential Mortgage-backed securities U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	1,365	1,588
Available-for-sale securities, at fair value	684,564	659,120
Recurring [Member] | Fair Value [Member] | Obligations of U.S. states and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	73,573	71,510
Recurring [Member] | Fair Value [Member] | Residential Mortgage-backed securities U.S. Government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	105,106	109,926
Recurring [Member] | Fair Value [Member] | Residential Mortgage-backed securities Non-U.S. Government agencies or sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	262	271
Recurring [Member] | Fair Value [Member] | U.S. corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	2,162	2,162
Recurring [Member] | Fair Value [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	955	1,427
Recurring [Member] | Level 2 [Member] | Other borrowings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other borrowings, fair value	10,920	10,961
Recurring [Member] | Level 2 [Member] | Obligations of U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	7,240	7,404
Available-for-sale securities, at fair value	583,304	557,820
Recurring [Member] | Level 2 [Member] | Residential Mortgage-backed securities U.S. Government sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value	1,365	1,588
Available-for-sale securities, at fair value	684,564	659,120
Recurring [Member] | Level 2 [Member] | Obligations of U.S. states and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	73,573	71,510
Recurring [Member] | Level 2 [Member] | Residential Mortgage-backed securities U.S. Government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	105,106	109,926
Recurring [Member] | Level 2 [Member] | Residential Mortgage-backed securities Non-U.S. Government agencies or sponsored entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	262	271
Recurring [Member] | Level 2 [Member] | U.S. corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	2,162	2,162
Recurring [Member] | Level 3 [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 955	$ 1,427