Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. Federal benefit at statutory rate	$ (3,395)	$ (9,417)
State and local (benefit) / expense net of U.S. federal tax	0	(1,641)
Permanent non deductible expenses for U.S. taxes	11	107
AMT credit benefit		(576)
Change in state deferred	2,799	0
Return to actual	(177)	0
Other true ups	(1,949)	0
Effect of change in deferred tax rate	0	29,809
Valuation allowance for deferred tax assets	2,711	(29,809)
Tax provision benefit	$ 0	$ (11,527)