Borrowings (Schedule of Long-Term Bank Loans Excluding Current Portion) (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total long-term bank loans, excluding current portion	$ 188,183,909	$ 111,808,244
Secured loans [Member]
Debt Instrument [Line Items]
Total long-term bank loans, excluding current portion	76,433,573	2,177,985
Unsecured loans [Member]
Debt Instrument [Line Items]
Total long-term bank loans, excluding current portion	199,807,529	196,031,589
Syndicate loan facility [Member]
Debt Instrument [Line Items]
Total long-term bank loans, excluding current portion	90,000,000	90,000,000
Current Portion [Member]
Debt Instrument [Line Items]
Total long-term bank loans, excluding current portion	$ 178,057,193	$ 176,401,330

Carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the operating cycle if longer, excluding current portion.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Name:	us-gaap_LongTermLoansFromBank
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant