Securities (Securities held to maturity (debt maturities)) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Amortized Cost
Due in 1 year or less	$ 2,486
Due in 1 to 5 years	27,627
Due in 5 to 10 years	104,170
Due after 10 years	115,483
Amortized Cost	249,766	$ 253,550
Estimated Fair Value
Due in 1 year or less	2,523
Due in 1 to 5 years	28,231
Due in 5 to 10 years	106,538
Due after 10 years	121,346
Estimated Fair Value	$ 258,638	$ 265,494

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Fair value of held-to-maturity 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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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the fifth through tenth fiscal year following the latest fiscal year.

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Fair value of held-to-maturity 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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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the next fiscal year through the fifth fiscal year following the latest fiscal year.

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Fair value of held-to-maturity 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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Fair value of held-to-maturity 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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