Summary of Significant Accounting Policies - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Item Effected [Line Items]
Selling, general and administrative expenses	$ 263,361	$ 252,995
Non-operating expenses	$ 7,486	5,847
As Reported
Item Effected [Line Items]
Selling, general and administrative expenses		258,045
Non-operating expenses		797
Reclassification
Item Effected [Line Items]
Selling, general and administrative expenses		(5,050)
Non-operating expenses		$ 5,050