Commitments and Contingencies (Details) $ in Thousands	Jun. 21, 2018 USD ($)	May 10, 2017 USD ($)	Jun. 30, 2018 USD ($) operating_lease states	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 operating_lease
Loss Contingencies [Line Items]
Number of operating leases settlements | states			3
Accrued lease settlement liability			$ 100
Other current liabilities			4,220	$ 5,487	$ 5,529
Pending Litigation | Cantor Fitzgerald & Co. | Damages Under Commercial Contract
Loss Contingencies [Line Items]
Loss contingency, damages sought	$ 4,000
Provant
Loss Contingencies [Line Items]
Litigation settlement amount		$ 800
Provant
Loss Contingencies [Line Items]
Accrued purchased commitment obligation related to vendor			1,300
Other Current Liabilities | Employment-related claim
Loss Contingencies [Line Items]
Loss contingency accrual			400
Other Current Liabilities | Provant
Loss Contingencies [Line Items]
Other current liabilities			100
Employee Severance | Other Current Liabilities
Loss Contingencies [Line Items]
Restructuring reserve			$ 600		$ 600
Maximum | Deferred Bonus
Loss Contingencies [Line Items]
One-time cash bonus percentage of gross enterprise value	5.00%
Minimum | Deferred Bonus
Loss Contingencies [Line Items]
One-time cash bonus percentage of gross enterprise value	4.00%
Olathe, KS and East Greenwich, RI
Loss Contingencies [Line Items]
Number of properties under operating leases | operating_lease			2
Des Moines, IA and Indianapolis
Loss Contingencies [Line Items]
Number of properties under operating leases | operating_lease						2