Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2015	Aug. 31, 2014	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2013
Income Statement [Abstract]
Net sales	$ 486.5	$ 441.0	$ 457.8	$ 323.0	$ 443.6	$ 420.4	$ 406.6	$ 331.6	$ 780.8	$ 738.2	$ 1,221.8	$ 1,158.6	$ 1,708.3	$ 1,602.2	$ 1,378.1
Operating costs and expenses:
Cost of sales (exclusive of items shown separately below)	428.3	373.1	372.7	285.4	373.9	375.8	369.0	287.5	658.1	656.5	1,031.2	1,032.3	1,459.5	1,406.2	1,234.3
AR1 research and development		8.3	2.2						2.2		10.5		32.1	0.0	0.0
Selling, general and administrative		11.5	13.6	15.6	9.9	9.8	8.9	9.6	29.2	18.5	40.7	28.3	49.0	38.2	53.6
Depreciation and amortization		16.1	16.1	16.3	17.3	15.7	15.8	14.9	32.4	30.7	48.5	46.4	65.1	63.7	43.5
Other expense, net:
Loss on debt repurchased		1.1	0.5	0.2	0.0	9.8	45.9	4.9	0.7	50.8	1.8	60.6	1.9	60.6	5.0
Legal settlement		50.0									50.0		50.0	0.0	0.0
Other		29.3	2.3	1.5	2.3	6.5	2.6	2.5	3.8	5.1	33.1	11.6	17.4	13.9	28.9
Total operating costs and expenses		489.4	407.4	319.0	403.4	417.6	442.2	319.4	726.4	761.6	1,215.8	1,179.2	1,675.0	1,582.6	1,365.3
Operating (loss) income		(48.4)	50.4	4.0	40.2	2.8	(35.6)	12.2	54.4	(23.4)	6.0	(20.6)	33.3	19.6	12.8
Non-operating (income) expense:
Interest income		(0.1)	0.0	(0.1)	(0.1)	0.0	0.0	0.0	(0.1)	0.0	(0.2)	0.0	(0.3)	(0.1)	(0.2)
Interest expense		11.9	13.2	13.4	13.7	14.0	12.6	12.4	26.6	25.0	38.5	39.0	50.4	52.7	48.7
Total non-operating expense, net		11.8	13.2	13.3	13.6	14.0	12.6	12.4	26.5	25.0	38.3	39.0	50.1	52.6	48.5
(Loss) income from continuing operations before income taxes	15.5	(60.2)	37.2	(9.3)	26.6	(11.2)	(48.2)	(0.2)	27.9	(48.4)	(32.3)	(59.6)	(16.8)	(33.0)	(35.7)
Income tax provision (benefit)		(21.7)	19.9	(5.8)	14.6	(0.5)	0.2	2.0	14.1	2.2	(7.6)	1.7	0.3	16.3	(198.4)
(Loss) income from continuing operations	7.6	(38.5)	17.3	(3.5)	12.0	(10.7)	(48.4)	(2.2)	13.8	(50.6)	(24.7)	(61.3)	(17.1)	(49.3)	162.7
Income (loss) from discontinued operations, net of income taxes	0.1	0.6	0.0	0.2	(0.1)	0.2	(0.8)	0.0	0.2	(0.8)	0.8	(0.6)	0.9	(0.7)	0.2
Net (loss) income	$ 7.7	$ (37.9)	$ 17.3	$ (3.3)	$ 11.9	$ (10.5)	$ (49.2)	$ (2.2)	$ 14.0	$ (51.4)	$ (23.9)	$ (61.9)	$ (16.2)	$ (50.0)	$ 162.9
Basic:
(Loss) income per share from continuing operations (in USD per share)	$ 0.12	$ (0.62)	$ 0.28	$ (0.06)	$ 0.20	$ (0.19)	$ (0.84)	$ (0.04)	$ 0.23				$ (0.28)	$ (0.85)	$ 2.68
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00	0.01	0.00	0.00	0.00	0.00	(0.01)	0.00	0.00				0.01	(0.01)	0.00
Net (loss) income per share (in USD per share)	0.12	(0.61)	0.28	(0.06)	0.20	(0.19)	(0.85)	(0.04)	0.23				(0.27)	(0.86)	2.68
Diluted:
(Loss) income per share from continuing operations (in USD per share)	0.12	(0.62)	0.25	(0.06)	0.18	(0.19)	(0.84)	(0.04)	0.22				(0.28)	(0.85)	2.05
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00	0.01	0.00	0.00	0.00	0.00	(0.01)	0.00	0.00				0.01	(0.01)	0.00
Net (loss) income per share (in USD per share)	$ 0.12	$ (0.61)	$ 0.25	$ (0.06)	$ 0.18	$ (0.19)	$ (0.85)	$ (0.04)	$ 0.22				$ (0.27)	$ (0.86)	$ 2.05
Weighted average shares of common stock outstanding, basic (in shares)			61.2	58.9	56.9				59.9				61.1	57.9	59.6
Weighted average shares of common stock outstanding, diluted (in shares)			72.3	58.9	72.0				72.2				61.1	57.9	81.9