Derivative Financial Instruments - Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Other Assets
Gross position	$ 38,746	$ 5,238
Impact of master netting agreement	(11,253)	(4,045)
Derivative values with impact of master netting agreements (as carried on balance sheet)	27,493	1,193
Cash collateral (held) pledged	(14,617)	(900)
Net position	12,876	293
Other Liabilities
Gross position	(40,855)	(28,688)
Impact of master netting agreement	11,253	4,045
Derivative values with impact of master netting agreements (as carried on balance sheet)	(29,602)	(24,643)
Cash collateral (held) pledged	47,604	72,478
Net position	$ 18,002	$ 47,835