Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Property and Equipment [Line Items]
Capitalized internal-use software, gross	$ 94,900		$ 92,700
Capitalized internal-use software, net	35,100		$ 33,600
Depreciation and amortization	42,598	$ 33,494
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	$ 35,300	$ 28,900