Derivative Instruments - Gross and Net Amounts of Derivative Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value of Assets
Gross derivative amounts recognized in the balance sheet	$ 862	$ 1,168
Gross derivative amounts not offset in the balance sheet that are eligible for offsetting	(473)	(52)
Net amount	389	1,116
Fair Value of Liabilities
Gross derivative amounts recognized in the balance sheet	1,258	1,452
Gross derivative amounts not offset in the balance sheet that are eligible for offsetting	(473)	(52)
Net amount	$ 785	$ 1,400

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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