Summary of Significant Accounting Policies - Concentration of Credit Risk (Details)	12 Months Ended
Dec. 31, 2018
Deposits \| Long-time Customer
Concentration of Credit Risk
Percentage of concentration of risk	11.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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