Fair Value Measurements Assets measured on a recurring basis, unobservable input reconciliation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 0.5	$ 1.2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liabilities, Fair Value Adjustment	0.1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	(0.8)
Encryptx [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	0	0.6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liabilities, Fair Value Adjustment	0.2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	(0.8)
MXI Security
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	0.5	0.6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liabilities, Fair Value Adjustment	(0.1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	$ 0