Balance Sheet Offsetting (Details) - Interest and commodity agreements - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 24,322	$ 18,031
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	24,322	18,031
Financial instruments	(16,517)	(18,031)
Collateral	(7,805)	0
Net amount	0	0
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	16,517	31,075
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	16,517	31,075
Financial instruments	(16,517)	(18,031)
Collateral	0	(11,148)
Net amount	$ 0	$ 1,896

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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