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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Accounting Policies [Abstract]    
Fair value assets transferred from level 1 to level 2 $ 0 $ 0
Fair value assets transferred from level 2 to level 1 0 0
Fair value liabilities transferred from level 1 to level 2 0 0
Fair value liabilities transferred from level 2 to level 1 0 0
Fair value measurement with unobservable inputs reconciliation recurring basis asset transfers net 0 0
Fair value measurement with unobservable inputs reconciliation recurring basis liabilities transfers net $ 0 $ 0