Summary of Significant Accounting Policies (Details 2) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Cash and Cash Equivalents        
Carrying value of cash and cash equivalents $ 33,311,000 $ 19,587,000 $ 21,744,000 $ 27,506,000
Carrying value of restricted cash $ 800,000 $ 800,000