Commitments and Contingencies - Lease Exit Liability (Details) - Facility Closing - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		$ (133,000)
Restructuring Reserve [Roll Forward]
Beginning balance	$ 1,354,000
Cash Payments	(337,000)
Ending balance	1,017,000
Expense	$ 5,200,000