Derivative Instruments-Balance Sheet Location - (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Offsetting Derivative Assets
Gross amounts recognized	$ 1,543	$ 5
Gross amounts offset in the consolidated balance sheets	0	0
Net amounts presented in the consolidated balance sheets	1,543	5
Financial instruments	130	5
Financial collateral pledged	0	0
Net amounts	1,413	0
Offsetting Derivative Liabilities
Gross amounts recognized	4,548	5,182
Gross amounts offset in the consolidated balance sheets	0	0
Net amounts presented in the consolidated balance sheets	4,548	5,182
Financial instruments	130	5
Financial collateral pledged	4,418	4,879
Net amounts	$ 0	$ 298