Organization and Basis of Presentation Prior period adjustments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Prior Period Adjustments [Line Items]
Net cash provided by operating activities	$ 198,623	$ 182,934
Accounting Standards Update 2016-18 [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		182,934
Accounting Standards Update 2016-18 [Member] | Scenario, Previously Reported [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		177,832
Accounting Standards Update 2016-18 [Member] | Restatement Adjustment [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		$ 5,102