Commitments rented properties data (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended				53 Months Ended	12 Months Ended	53 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Lease- Mountain View, CA 590 Middlefield road [Member]	Jun. 30, 2012 Lease- Mountain View, CA 590 Middlefield road [Member] sqft	Dec. 31, 2012 Lease - Milpitas, CA 735 Sycamore Drive [Member]	Jun. 30, 2012 Lease - Milpitas, CA 735 Sycamore Drive [Member] sqft	Dec. 31, 2012 Lease - St. Petersburg, FL 2003 gaudy Bldvd. North [Member] sqft	Dec. 31, 2012 lease - Leeds, United Kingdom [Member]
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	$ 5.7	$ 3.3	$ 3.6
Operating Leases, Income Statement, Sublease Revenue		0.5
property subject to operating lease, net rentable area					100,000		46,000	132,500
property subject to operating lease term duration					10 years		60 months
Operating Leases, Rent Expense, Minimum Rentals					$ 40.0		$ 1.8	$ 3.9	$ 1.2
property subject to lease, 1st extension term duration								12 years	10 years
Lease Expiration Date									Jun. 08, 2021
property subject to lease, 1st extension term duration				60 months		60 months		60 months	0
Property subject to operating lease, 2nd extension term duration				60 months				60 months