Annual report pursuant to Section 13 and 15(d)

Certain Risks and Concentrations (Details)

v3.8.0.1
Certain Risks and Concentrations (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Major suppliers [Member] | A (Hong Fa Shipping Limited, a related party) [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage 23.00% 44.00% 30.00%
Major suppliers [Member] | B (Hong Long, a related party) [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage 26.00% [1] 11.00%
Major suppliers [Member] | C [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage 13.00% [1] [1]
Major suppliers [Member] | D (Hai Yi Shipping Limited, a related party) [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage [1] 25.00% 14.00%
Major suppliers [Member] | E [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage [1] 13.00% [1]
Major suppliers [Member] | F (PT Avona Mina Lestari, a related party) [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage [1] [1] 34.00%
Major customers [Member] | A [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage [1] 11.00%
Major customers [Member] | B [Member]      
Concentration Risk [Line Items]      
Concentration risk, Percentage [1] 10.00%
[1] less than 10%