Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Rent expense		$ 14,000	$ 14,300	$ 10,700
Bank Loan [Member]
Proceeds from secured loan	$ 26,000

The cash inflow from amounts received from issuance of long-term debt that is wholly or partially secured by collateral. Excludes proceeds from tax exempt secured debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Name:	us-gaap_ProceedsFromIssuanceOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration