Net Loss Per Share and Shareholders' Equity - Reconciliation of Numerator and Denominator of the Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator:
Net earnings (loss)	$ 6.7	$ (11.2)	$ 29.4	$ (54.3)
Denominator:
Denominator for basic EPS–weighted-average common shares (in shares)	67,567,671	66,900,081	67,389,370	57,529,038
Dilutive effect of stock-based compensation arrangements (in shares)	2,661,031	0	2,630,117	0
Denominator for diluted EPS–adjusted weighted-average common shares (in shares)	70,228,702	66,900,081	70,019,487	57,529,038
Basic EPS (in dollars per share)	$ 0.10	$ (0.17)	$ 0.44	$ (0.94)
Diluted EPS (in dollars per share)	$ 0.10	$ (0.17)	$ 0.42	$ (0.94)