Summary of Significant Accounting Policies - Fair Value of Financial Instruments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 28,338	$ 10,380	$ 11,012
Restricted cash	373	693	1,078
Restricted cash and investments for Development Projects	21,039	136,431
Restricted cash and cash equivalents for Development Projects	21,039	41,982	$ 26,384
Short-term marketable securities	94,500	94,500
Short-term Investments, Fair Value Disclosure	94,200
Long-term Debt	543,697	469,736
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		10,380
Cash and Cash Equivalents, Fair Value Disclosure	28,338	10,380
Restricted cash		693
Restricted Cash and Cash Equivalents, Current, Fair Value Disclosure	373	693
Restricted cash and cash equivalents for Development Projects		41,982
Restricted Cash, Noncurrent, Fair Value Disclosure	21,039	41,982
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities	0	94,449
Short-term Investments, Fair Value Disclosure	0	94,209
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Payable, Fair Value Disclosure	30,954	0
Notes Payable, Related Parties	30,954	0
Bangkok Bank Loan [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lines of Credit, Fair Value Disclosure	20,000	16,000
Long-term Line of Credit	20,000	16,000
Fifth Third Revolver [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lines of Credit, Fair Value Disclosure	15,000	0
Long-term Line of Credit	15,000	0
Equipment Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	20,400	31,100
Equipment Loans [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	20,384	31,095
Lines of Credit, Fair Value Disclosure	20,384	31,095
Interest Rate Cap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	143	251
Forward Contracts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	1,865	0
Initial Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	900
Initial Put Option [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	879	0
Put Option MHHA [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	2,300	0
Notes Payable to Banks [Member] | Term Loan Facility, Term B Loan [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	440,803	443,161
Notes Payable, Fair Value Disclosure	440,660	449,749
Notes Payable to Banks [Member] | Term Loan Facility, Term A Loan [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	64,750	0
Notes Payable, Fair Value Disclosure	64,750	0
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities		59,400
US Treasury Notes Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities		35,100
Series F | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, at Fair Value	$ 31,122	$ 0