Share-Based Compensation and Employee Ownership Plans Restricted Shares and Restricted Stock Units (Details) - Equity Plans - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Weighted-Average Grant Date Fair Value
Allocated Share-based Compensation Expense		$ 5.3	$ 3.8	$ 16.2	$ 14.3
Restricted Shares and Restricted Stock Units (RSUs)
Nonvested Restricted Shares and Restricted Stock Units
Balance outstanding, beginning of period, shares				17,654,582
Granted, shares				5,718,605
Vested, shares				(3,992,005)
Cancelled, shares				0
Forfeited, shares				(1,017,758)
Balance outstanding, end of period, shares	[1]	18,363,424		18,363,424
Weighted-Average Grant Date Fair Value
Balance outstanding, beginning of period, in dollars per share				$ 3.70
Granted, in dollars per share				4.79
Vested, in dollars per share				3.08
Cancelled, in dollars per share				0.00
Forfeited, in dollars per share				3.41
Balance outstanding, end of period, in dollars per share	[1]	$ 4.19		$ 4.19
Unrecognized compensation expense		$ 52.7		$ 52.7
Weighted-average recognition period for unrecognized compensation expense				1 year 7 months 27 days
Performance based restricted stock
Nonvested Restricted Shares and Restricted Stock Units
Granted, shares				1,925,750
Forfeited, shares				(326,250)

[1] Performance linked restricted stock units of 1,925,750 were awarded to employees of the Company in December 2013 and January 2014. Of the awards granted, 326,250 have been forfeited through September 30, 2015. The remaining awards, included in the outstanding balance as of September 30, 2015, will vest on June 10, 2019 and will be earned only to the extent that the Company attains specified performance goals relating to its volume-weighted average share price and the aggregate net income for the years from 2014 to 2018. The actual number of RSUs ultimately earned could vary from zero, if performance goals are not met, to as much as 100% of the targeted award. Each RSU is equal to the one share of the Company’s Class A common stock. Compensation expense is recognized to the extent that it is probable that the Company will attain the performance goals.