Securities Available-for-Sale - Amortized Cost and Fair Value of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 686,205	$ 650,782
Fair Value	693,487	660,963
Obligations of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	52,594
Due after one year through five years, Amortized Cost	201,450
Due after five years through ten years, Amortized Cost	64,569
Due after ten years, Amortized Cost	66,050
Available-for-sale Securities, Debt Maturities, Amortized Cost	384,663
Due in one year or less, Fair Value	52,696
Due after one year through five years, Fair Value	203,513
Due after five years through ten years, Fair Value	64,975
Due after ten years, Fair Value	68,315
Fair Value, Debt securities	389,499
Collateralized mortgage obligations of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	130,046	128,458
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
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
Fair Value	125,604	69,204
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	678,626	643,203
Fair Value	682,238	651,294
Marketable equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,579	7,579
Fair Value	$ 11,249	$ 9,669

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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

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Amount after adjustments of available-for-sale debt securities at cost, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Fair value of available-for-sale debt securities maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after adjustments of available-for-sale debt securities at cost, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Fair value of available-for-sale debt securities maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after adjustments of available-for-sale debt securities at cost, maturing after the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Fair value of available-for-sale debt securities maturing after the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after adjustments of available-for-sale debt securities at cost, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Fair value of available-for-sale debt securities maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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