Basis of Presentation and Significant Accounting Policies - Depreciation and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	$ 134,504	$ 126,873	$ 265,725	$ 251,131
Depreciation of property, plant and equipment
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	7,065	6,204	12,984	12,377
Amortization of capitalized contract costs
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	107,245	97,937	212,275	193,302
Amortization of definite-lived intangibles
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	$ 20,194	$ 22,732	$ 40,466	$ 45,452