Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment [Line Items]
Capitalized internal-use software, gross	$ 138,200	$ 122,000
Capitalized internal-use software, net	31,500	26,500
Depreciation and amortization	235,482	212,930	$ 188,049
Accrued capital expenditures	5,200	4,000
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	$ 212,500	$ 192,300	$ 167,200