Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment [Line Items]
Capitalized internal-use software, gross	$ 101,400	$ 92,700
Capitalized internal-use software, net	33,400	33,600
Depreciation and amortization	169,662	154,452	$ 140,926
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	$ 141,300	$ 129,400	$ 119,700