Summary of Significant Accounting Policies (Details 4) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Accrued other expense	$ 7,045	$ 7,001
Accounts payable	4,321	7,791
New build liability	3,817	2,730
Employee liability	2,744	2,644
Royalty payable	1,605	1,673
Income tax liabilities	1,368	1,490
Bonus compensation liabilty	1,276	3,736
Travel certificate liability	1,128	1,120
Refunds and commissions payable	926	1,805
Accrued travel insurance expense	472	432
Total accounts payable and accrued expenses	$ 24,702	$ 30,422