Organization and Basis of Presentation Prior period adjustments (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Prior Period Adjustments [Line Items]
Net cash provided by operating activities	$ 296,445	$ 264,917
Accounting Standards Update 2016-18 [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		264,917
Previously Reported [Member] \| Accounting Standards Update 2016-18 [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		261,587
Restatement Adjustment [Member] \| Accounting Standards Update 2016-18 [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		$ 3,330

Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration