Basis of Presentation and Summary of Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows from operating activities	$ 185,626	$ 177,506
Net cash flows from investing activities	$ (293,687)	(178,934)
As Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows from operating activities		176,013
Net cash flows from investing activities		(177,154)
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows from operating activities		1,493
Net cash flows from investing activities		$ (1,780)