Securities Available-for-Sale - Composition of Securities Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 686,205	$ 650,782
Gross Unrealized Gains	10,754	11,897
Gross Unrealized Losses	(3,472)	(1,716)
Fair Value	693,487	660,963
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	24,891	14,914
Gross Unrealized Gains	47	27
Gross Unrealized Losses	(127)	0
Fair Value	24,811	14,941
Obligations of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	230,989	262,045
Gross Unrealized Gains	1,573	1,825
Gross Unrealized Losses	(383)	(567)
Fair Value	232,179	263,303
Collateralized mortgage obligations of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	130,046	128,458
Gross Unrealized Gains	465	693
Gross Unrealized Losses	(734)	(316)
Fair Value	129,777	128,835
Residential mortgage-backed securities of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	36,606	39,185
Gross Unrealized Gains	984	1,091
Gross Unrealized Losses	(232)	(151)
Fair Value	37,358	40,125
Commercial mortgage-backed securities of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	127,311	69,697
Gross Unrealized Gains	243	183
Gross Unrealized Losses	(1,950)	(676)
Fair Value	125,604	69,204
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	128,783	128,904
Gross Unrealized Gains	3,772	5,988
Gross Unrealized Losses	(46)	(6)
Fair Value	132,509	134,886
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	678,626	643,203
Gross Unrealized Gains	7,084	9,807
Gross Unrealized Losses	(3,472)	(1,716)
Fair Value	682,238	651,294
Marketable equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,579	7,579
Gross Unrealized Gains	3,670	2,090
Gross Unrealized Losses	0	0
Fair Value	$ 11,249	$ 9,669

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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