Derivative Instruments and Hedging Activities- Effects on Statements of Income and Consolidated Statements of Comprehensive income (Loss) (Details) - USD ($) $ in Thousands  | 
3 Months Ended | |
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Mar. 31, 2016  | 
Mar. 31, 2015  | 
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| Derivatives Designated as Hedging Instruments | Interest rate swap instruments | ||
| Derivative Instruments, Gain (Loss) [Line Items] | ||
| Amount of Gain Recognized in Net Income | $ 70 | $ 83 | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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