Acquisition Acquisition (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								6 Months Ended	12 Months Ended
	Jul. 01, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Document Fiscal Year Focus											2016
Revenues		$ 240.6	$ 243.1	$ 190.3	$ 185.3	$ 223.5	$ 246.7	$ 192.8	$ 186.6		$ 859.3	$ 849.6	$ 915.0
Net (loss) earnings		$ 19.3	$ (7.6)	$ (24.6)	$ (29.4)	$ (187.0)	$ (14.9)	$ (16.1)	$ (15.8)		$ (42.3)	$ (233.8)	$ (87.0)
Audience, Inc.
Business Acquisition [Line Items]
Cash equivalent price (usd per share)	$ 2.51
Consideration transfer, number of shares for each share of acquired entity's shares (in shares)	0.13207
Number of shares issued (in shares)	3,200,000
Fair value of total consideration	$ 123.3
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Number of Shares for Unvested Equity Awards Assumed	461,371.00
Consideration transferred, enterprise value, net of cash and short-term investments	$ 92.8
Cash and short-term investments	$ 30.5
Revenues										$ 19.0
Net (loss) earnings										$ 31.6
Fair Value Inputs, Discount Rate	27.00%