Stock-Based Compensation (Stock-based Compensation Expense) (Details) $ in Thousands	Mar. 31, 2018 USD ($)
Share-based Compensation [Abstract]
2018	$ 3,614
2019	3,856
2020	2,397
2021	552
2022	39
Total	$ 10,458

Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant