Balance Sheet Offsetting (Tables)

12 Months Ended

Dec. 31, 2015

Offsetting [Abstract]

Balance Sheet Offsetting of Derivative Assets and Liabilities

The following table presents the assets and liabilities subject to an enforceable master netting arrangement. The interest and commodity agreements we have with our commercial customers are not subject to an enforceable master netting arrangement, and therefore, are excluded from this table.

	Gross amounts recognized						Gross amounts not offset in the balance sheet
			Gross amounts offset in the balance sheet		Net amounts presented in the balance sheet		Financial instruments			Collateral			Net amount
	($ in Thousands)
December 31, 2015
Derivative assets:
Interest and commodity agreements	$	1,466	$	—	$	1,466	$	(1,466	)	$	—		$	—
Derivative liabilities:
Interest and commodity agreements	$	30,200	$	—	$	30,200	$	(1,466	)	$	(28,734	)	$	—
December 31, 2014
Derivative assets:
Interest rate-related instruments	$	558	$	—	$	558	$	(558	)	$	—		$	—
Derivative liabilities:
Interest rate-related instruments	$	34,087	$	—	$	34,087	$	(558	)	$	(26,105	)	$	7,424