Derivative Instruments-Balance Sheet Location (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Offsetting Derivative Assets
Gross amounts recognized	$ 3,864	$ 4,654
Gross amounts offset in the consolidated balance sheets	0	0
Net amounts presented in the consolidated balance sheets	3,864	4,654
Derivative, FairValue, Liabilities, Not Offset	584	0
Financial collateral pledged	0	0
Net amounts	3,280	4,654
Offsetting Derivative Liabilities
Gross amounts recognized	4,784	5,514
Gross amounts offset in the consolidated balance sheets	0	0
Net amounts presented in the consolidated balance sheets	4,784	5,514
Derivative, Fair Value, Assets, Not Offset	584	0
Financial collateral pledged	2,183	4,950
Net amounts	$ 2,017	$ 564