Income Tax (Details 5) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Income Tax  
Preferential income tax rate (as a percent) 5.00%
Minimum  
Income Tax  
Amount of Unrecognized deferred tax liabilities 19.0
Withholding tax rate of profit distribution 5.00%
Maximum  
Income Tax  
Amount of Unrecognized deferred tax liabilities 38.0
Withholding tax rate of profit distribution 10.00%