Equity Method Investments (Details)	Dec. 31, 2017 ventures
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	7
Chile
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	1
India
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	1
Saudi Arabia
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	1
South Korea
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	1
United Arab Emirates
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	1
China
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures	2