Income Taxes - Reconciliation of statutory to effective income tax rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal Statutory Rate	21.00%	35.00%	35.00%
Permanent differences	(25.70%)	57.50%	7.70%
State taxes, net of Federal benefit	3.50%	(6.60%)	6.10%
Rate change	(0.60%)	370.50%	(4.20%)
Foreign earnings taxed at different rates than U.S.	11.80%	(40.50%)	(13.50%)
Valuation allowance	81.20%	(401.40%)	(27.50%)
Transition tax	(13.80%)	0.00%	0.00%
Net operating loss expiration and remeasurement	(75.80%)	0.00%	0.00%
Transition tax	(1.40%)	3.80%	(1.00%)
Other	0.10%	(4.60%)	(3.70%)
Effective tax rate	0.30%	13.70%	(1.10%)