|
Employee Benefit Plans (Details) (USD $)
|
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
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| Employee Benefit Plans | |||
| Contribution to employee benefit plans | $ 58,365,171 | $ 45,924,681 | $ 40,724,902 |