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Revenue from Contracts with Customers - Summary of Changes in Deferred Revenue (Details) - USD ($)
6 Months Ended 12 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Revenue Recognition and Deferred Revenue [Abstract]    
Beginning balance $ 15,824 $ 24,442
Revenue recognized in the current period from the amounts in the beginning balance (5,831) (14,450)
New deferrals, net of amounts recognized in the current period   5,832
Ending balance $ 9,993 $ 15,824