Summary of Significant Accounting Policies - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Item Effected [Line Items]
Selling, general and administrative expenses	$ 276,345	$ 255,612	$ 810,474	$ 760,714
Non-operating expenses	$ 7,828	6,357	$ 22,841	18,503
As Reported
Item Effected [Line Items]
Selling, general and administrative expenses		260,752		776,135
Non-operating expenses		1,217		3,082
Reclassification
Item Effected [Line Items]
Selling, general and administrative expenses		(5,140)		(15,421)
Non-operating expenses		$ 5,140		$ 15,421