Operating Segments and Related Disclosures - Schedule of Selected Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		9 Months Ended
	May. 31, 2015	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2014
Net Sales:
Net sales	$ 456.9	$ 421.2	$ 404.5	$ 332.1	$ 775.5	$ 736.6
Segment Performance:
Unusual items	(0.5)		(46.2)		0.0	(51.1)
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Interest expense	(13.2)		(12.6)		(26.6)	(25.0)
Interest income	0.0		0.0		0.1	0.0
Stock-based compensation expense	(2.0)		(1.6)		(7.3)	(3.0)	$ (4.5)
Unusual items	(0.5)		(46.2)		0.0	(51.1)
Income (loss) from continuing operations before income taxes	39.7		(50.7)		29.0	(51.2)
Operating Segments [Member]
Net Sales:
Net sales	456.9		404.5		775.5	736.6
Segment Performance:
Total Segment Performance	65.7		16.9		83.8	43.1
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Segment performance	65.7		16.9		83.8	43.1
Operating Segments [Member] | Aerospace and Defense [Member]
Net Sales:
Net sales	413.4		402.9		730.4	733.5
Segment Performance:
Aerospace and Defense	48.4		22.5		78.7	55.5
Environmental remediation provision adjustments	(1.9)		(0.3)		(3.3)	(1.9)
Retirement benefit plan expense	(12.4)		(6.1)		(24.8)	(12.2)
Unusual items	0.0		(0.1)		0.7	(0.1)
Total Segment Performance	34.1		16.0		51.3	41.3
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Segment performance	34.1		16.0		51.3	41.3
Corporate retirement benefit plan expense	(12.4)		(6.1)		(24.8)	(12.2)
Unusual items	0.0		(0.1)		0.7	(0.1)
Operating Segments [Member] | Real Estate [Member]
Net Sales:
Net sales	43.5		1.6		45.1	3.1
Segment Performance:
Total Segment Performance	31.6		0.9		32.5	1.8
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Segment performance	31.6		0.9		32.5	1.8
Segment Reconciling Items [Member]
Segment Performance:
Unusual items	(0.5)		(46.1)		(0.7)	(51.0)
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Interest expense	(13.2)		(12.6)		(26.6)	(25.0)
Interest income	0.0		0.0		0.1	0.0
Stock-based compensation expense	(2.0)		(1.6)		(7.3)	(3.0)
Unusual items	(0.5)		(46.1)		(0.7)	(51.0)
Corporate, Non-Segment [Member]
Segment Performance:
Retirement benefit plan expense	(4.4)		(2.8)		(8.6)	(5.6)
Reconciliation of segment performance to income (loss) from continuing operations before income taxes:
Corporate retirement benefit plan expense	(4.4)		(2.8)		(8.6)	(5.6)
Corporate and other expense, net	$ (5.9)		$ (4.5)		$ (11.7)	$ (9.7)