Basic and Diluted Loss Per Common Share - Loss Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income (numerator)
Net loss from continuing operations	$ (47.1)	$ (69.8)	$ (72.4)	$ (45.0)	$ (0.5)	$ (0.4)	$ (12.4)	$ (12.3)	$ (12.4)	$ (24.5)	$ (10.9)	$ 3.9	$ (234.3)	$ (25.6)	$ (43.9)
Net loss from discontinued operations	0	0	0	0	(3.0)	(0.1)	(0.6)	(0.9)	(12.3)	(2.6)	(1.7)	(2.1)	0	(4.6)	(18.7)
Net loss	$ (47.1)	$ (69.8)	$ (72.4)	$ (45.0)	$ (3.5)	$ (0.5)	$ (13.0)	$ (13.2)	$ (24.7)	$ (27.1)	$ (12.6)	$ 1.8	$ (234.3)	$ (30.2)	$ (62.6)
Shares (denominator)
Basic weighted-average common shares outstanding (in shares)	84.9	84.7	84.4	84.3	85.2	85.1	85.0	84.6	84.9	90.0	92.8	92.5	84.6	85.0	90.0
Diluted weighted-average common shares outstanding (in shares)	84.9	84.7	84.4	84.3	85.2	85.1	85.0	84.6	84.9	90.0	92.8	94.2	84.6	85.0	90.0
Basic and diluted earnings per share:
Basic net loss per share from continuing operations (in dollars per share)	$ (0.55)	$ (0.82)	$ (0.86)	$ (0.53)	$ (0.01)	$ (0.01)	$ (0.14)	$ (0.15)	$ (0.15)	$ (0.27)	$ (0.12)	$ 0.04	$ (2.77)	$ (0.30)	$ (0.49)
Basic net loss per share from discontinued operations (in dollars per share)	$ 0.00	$ 0	$ 0.00	$ 0.00	$ (0.03)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.14)	$ (0.03)	$ (0.02)	$ (0.02)	$ 0.00	$ (0.06)	$ (0.21)
Total basic net loss per share (in dollars per share)	$ (0.55)	$ (0.82)	$ (0.86)	$ (0.53)	$ (0.04)	$ (0.01)	$ (0.15)	$ (0.16)	$ (0.29)	$ (0.30)	$ (0.14)	$ 0.02	$ (2.77)	$ (0.36)	$ (0.70)
Diluted net loss per share from continuing operations (in dollars per share)	$ (0.55)	$ (0.82)	$ (0.86)	$ (0.53)	$ (0.01)	$ (0.01)	$ (0.14)	$ (0.15)	$ (0.15)	$ (0.27)	$ (0.12)	$ 0.04	$ (2.77)	$ (0.30)	$ (0.49)
Diluted net loss per share from discontinued operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.03)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.14)	$ (0.03)	$ (0.02)	$ (0.02)	$ 0.00	$ (0.06)	$ (0.21)
Total diluted net loss per share (in dollars per share)	$ (0.55)	$ (0.82)	$ (0.86)	$ (0.53)	$ (0.04)	$ (0.01)	$ (0.15)	$ (0.16)	$ (0.29)	$ (0.30)	$ (0.14)	$ 0.02	$ (2.77)	$ (0.36)	$ (0.70)