Accounting for Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) plan $ / shares shares	Sep. 30, 2015 USD ($) $ / shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shareholder-approved, share-based compensation plans | plan			2
Stock options outstanding (in shares) | shares	15,487,348		15,487,348
Aggregate intrinsic value of employee options outstanding	$ 9.2		$ 9.2
Intrinsic value of exercisable options	3.9		$ 3.9
Weighted average grant-date fair values of stock options (in dollars per share) | $ / shares			$ 1.08	$ 1.71
Unrecognized compensation cost, net of estimated forfeitures	7.1		$ 7.1
Intrinsic values of employee stock options exercised			0.5	$ 0.1
Fair values of vested stock options			2.8	2.1
Non-employee compensation expense, recognized expenses (reversals)	0.1	$ (0.1)	(0.1)	0.2
Stock options outstanding
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Compensation expense related to employee and director stock option grants	$ 1.6	$ 1.0	$ 3.3	$ 2.7
Vice Chairman of Board of Directors | Stock options outstanding
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period of options	24 months
Compensation expense related to employee and director stock option grants	$ 0.6
2010 Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (in shares) | shares			4,621,225
Vesting period of options			4 years
Unrecognized compensation cost, weighted average period for recognition			2 years 10 months 4 days
2010 Plan | Non-employee directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (in shares) | shares			470,000
Vesting period of options			1 year
Stock option granted, exercise price per share (in dollars per share) | $ / shares			$ 1.76
2010 Plan | Tranche one
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option			25.00%
2010 Plan | Tranche two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option			6.25%