Commitments and Contingent Liabilities - Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2016	Jun. 10, 2016
Operating Leased Assets [Line Items]
Rent expense net of sublease rental income	$ 8.7	$ 11.1	$ 7.7
Future operating lease payments	69.1
Capital Leases [Abstract]
2015	2.3
2016	2.3
2017	2.3
2018	2.3
2019	2.3
Thereafter	7.1
Total	18.6
Operating Lease Future Minimum Payments [Abstract]
2015	9.4
2016	8.8
2017	8.5
2018	8.1
2019	8.0
2020 and thereafter	26.3
Total	$ 69.1
Audience, Inc.
Operating Leased Assets [Line Items]
Loss Contingency Accrual				$ 0.4
Release and Attorney's Fees [Member]
Operating Leased Assets [Line Items]
Loss Contingency Accrual					$ 6.0
Other Litigation Costs [Member]
Operating Leased Assets [Line Items]
Loss Contingency Accrual					$ 1.9