Related-Party Transactions (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
Deferred compensation obligation	$ 4,149	$ 4,112
Fair value of common stock included in deferred compensation obligation	$ 16	$ 18

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

No definition available.

Name:	us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant