Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2011 Y
Computer equipment and related software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Minimum	2
Property, Plant and Equipment, Useful Life, Maximum	7
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Minimum	25
Property, Plant and Equipment, Useful Life, Maximum	32
Leasehold and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	Shorter of the lease term or the estimated useful life
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Minimum	3
Property, Plant and Equipment, Useful Life, Maximum	5
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Minimum	3
Property, Plant and Equipment, Useful Life, Maximum	5