Property and Equipment, net (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property and equipment
Property and equipment, at cost	$ 1,808,608,000	$ 1,412,051,000
Less accumulated depreciation and amortization	(983,618,000)	(738,274,000)
Work in process	65,786,000	51,208,000
Total property and equipment, net	890,776,000	724,985,000
Income statement disclosures
Depreciation and leasehold amortization expense	303,200,000	240,900,000	189,800,000
Computers, software and equipment
Property and equipment
Property and equipment, at cost	1,488,106,000	1,140,772,000
Computers, software and equipment | Minimum
Property and equipment
Estimated useful lives	1 year
Computers, software and equipment | Maximum
Property and equipment
Estimated useful lives	5 years
Furniture and fixtures
Property and equipment
Estimated useful lives	7 years
Property and equipment, at cost	55,681,000	40,557,000
Buildings and leasehold improvements
Property and equipment
Property and equipment, at cost	236,255,000	214,858,000
Buildings and leasehold improvements | Minimum
Property and equipment
Estimated useful lives	2 years
Buildings and leasehold improvements | Maximum
Property and equipment
Estimated useful lives	30 years
Land
Property and equipment
Property and equipment, at cost	28,566,000	15,864,000
Office facility build outs
Property and equipment
Work in process	32,600,000	28,400,000
Data center build outs
Property and equipment
Work in process	2,400,000	2,800,000
Capitalized computer software costs
Property and equipment
Estimated useful lives	36 months
Work in process	30,700,000	20,000,000
Total property and equipment, net	88,700,000	78,700,000
Income statement disclosures
Depreciation and leasehold amortization expense	$ 50,600,000	$ 36,400,000	$ 26,200,000