Fair Value Measurements - Summary of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets
Securities available for sale	$ 603,121	$ 460,797
State tax credits held for sale	1,274	3,585
Portion at Other than Fair Value, Fair Value Disclosure
Assets
State tax credits held for sale	34,000
Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	603,121	460,797
State tax credits held for sale	37,781	41,264
Derivative financial instruments	3,278	4,016
Liabilities
Derivative financial instruments	3,278	4,016
Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	100,123	107,660
Obligations of states and political subdivisions
Assets
Securities available for sale	33,342	36,631
Residential mortgage-backed securities
Assets
Securities available for sale	469,656	316,506
Recurring basis \| Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	603,121	460,797
State tax credits held for sale	1,274	3,585
Derivative financial instruments	3,278	4,016
Total assets	607,673	468,398
Liabilities
Derivative financial instruments		4,016
Total liabilities	3,278	4,016
Recurring basis \| Obligations of U.S. Government-sponsored enterprises \| Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	100,123	107,660
Recurring basis \| Obligations of states and political subdivisions \| Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	33,341	36,631
Recurring basis \| Residential mortgage-backed securities \| Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	469,657	316,506
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Securities available for sale	0	0
State tax credits held for sale	0	0
Derivative financial instruments	0	0
Total assets	0	0
Liabilities
Derivative financial instruments	0	0
Total liabilities	0	0
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	0	0
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Obligations of states and political subdivisions
Assets
Securities available for sale	0	0
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Residential mortgage-backed securities
Assets
Securities available for sale	0	0
Recurring basis \| Significant Other Observable Inputs (Level 2)
Assets
Securities available for sale	603,121	457,708
State tax credits held for sale	0	0
Derivative financial instruments	3,278	4,016
Total assets	606,399	461,724
Liabilities
Derivative financial instruments	3,278	4,016
Total liabilities	3,278	4,016
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	100,123	107,660
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Obligations of states and political subdivisions
Assets
Securities available for sale	33,341	33,542
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Residential mortgage-backed securities
Assets
Securities available for sale	469,657	316,506
Recurring basis \| Significant Unobservable Inputs (Level 3)
Assets
Securities available for sale	0	3,089
State tax credits held for sale	1,274	3,585
Derivative financial instruments	0	0
Total assets	1,274	6,674
Liabilities
Derivative financial instruments	0	0
Total liabilities	0	0
Recurring basis \| Significant Unobservable Inputs (Level 3) \| Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	0	0
Recurring basis \| Significant Unobservable Inputs (Level 3) \| Obligations of states and political subdivisions
Assets
Securities available for sale	0	3,089
Recurring basis \| Significant Unobservable Inputs (Level 3) \| Residential mortgage-backed securities
Assets
Securities available for sale	$ 0	$ 0

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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