Organization and Basis of Presentation Prior period adjustments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Prior Period Adjustments [Line Items]
Net cash provided by operating activities	$ 93,699	$ 84,480
Accounting Standards Update 2016-18 [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		84,480
Accounting Standards Update 2016-18 [Member] | Scenario, Previously Reported [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		86,382
Accounting Standards Update 2016-18 [Member] | Restatement Adjustment [Member]
Prior Period Adjustments [Line Items]
Net cash provided by operating activities		$ (1,902)