Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
AFS securities [Abstract]
Securities available for sale, at estimated fair value	$ 1,338,290	$ 1,174,544
Trading securities	9,259	8,377
Liabilities [Abstract]
Collateral dependent impaired financing receivable with specific reserves	7,000
Reserves on collateral dependent impaired loans	$ 1,500
Minimum [Member]
Liabilities [Abstract]
Liquidation expense ratio on impaired collateral	10.00%
Maximum [Member]
Liabilities [Abstract]
Liquidation expense ratio on impaired collateral	35.00%
Federal Agency [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	$ 174,408	311,272
State & Municipal [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	46,726	31,637
Other Securities [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	20,739	16,768
Recurring Basis [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	1,338,290	1,174,544
Trading securities	9,259	8,377
Interest rate swaps	3,210	6,224
Total	1,350,759	1,189,145
Liabilities [Abstract]
Interest rate swaps	506	6,224
Total	506	6,224
Recurring Basis [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	11,493	7,526
Trading securities	9,259	8,377
Interest rate swaps	0	0
Total	20,752	15,903
Liabilities [Abstract]
Interest rate swaps	0	0
Total	0	0
Recurring Basis [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	1,326,797	1,167,018
Trading securities	0	0
Interest rate swaps	3,210	6,224
Total	1,330,007	1,173,242
Liabilities [Abstract]
Interest rate swaps	506	6,224
Total	506	6,224
Recurring Basis [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Trading securities	0	0
Interest rate swaps	0	0
Total	0	0
Liabilities [Abstract]
Interest rate swaps	0	0
Total	0	0
Recurring Basis [Member] \| Federal Agency [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	174,408	311,272
Recurring Basis [Member] \| Federal Agency [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Federal Agency [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	174,408	311,272
Recurring Basis [Member] \| Federal Agency [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| State & Municipal [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	46,726	31,637
Recurring Basis [Member] \| State & Municipal [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| State & Municipal [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	46,726	31,637
Recurring Basis [Member] \| State & Municipal [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Mortgage-Backed [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	529,844	409,896
Recurring Basis [Member] \| Mortgage-Backed [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Mortgage-Backed [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	529,844	409,896
Recurring Basis [Member] \| Mortgage-Backed [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Collateralized Mortgage Obligations [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	566,573	404,971
Recurring Basis [Member] \| Collateralized Mortgage Obligations [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Collateralized Mortgage Obligations [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	566,573	404,971
Recurring Basis [Member] \| Collateralized Mortgage Obligations [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	0	0
Recurring Basis [Member] \| Other Securities [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	20,739	16,768
Recurring Basis [Member] \| Other Securities [Member] \| Level 1 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	11,493	7,526
Recurring Basis [Member] \| Other Securities [Member] \| Level 2 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	9,246	9,242
Recurring Basis [Member] \| Other Securities [Member] \| Level 3 [Member]
AFS securities [Abstract]
Securities available for sale, at estimated fair value	$ 0	$ 0

Collateral dependent impaired loans with specific reserves included in the allowance for loan losses.

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- Definition

Collateral dependent impaired loans which had specific reserves.

+ References

No definition available.

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- Definition

The percentage of liquidation expenses estimated with liquidating impaired collateral.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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Fair value of financial and nonfinancial obligations.

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- Definition

Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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