Consolidated Balance Sheets - USD ($) $ in Millions	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Nov. 30, 2012
Current Assets
Cash and cash equivalents	$ 211.1	$ 243.3	$ 253.5	$ 215.7	$ 265.9	$ 154.9	$ 120.7	$ 144.1	$ 197.6	$ 162.1
Accounts receivable	171.5	189.3	175.6	190.0	170.5	200.5	177.3	186.1
Inventories	157.5	147.9	150.1	161.5	138.0	131.8	131.7	136.2
Recoverable from the U.S. government and other third parties for environmental remediation costs	24.0	23.2	23.7	23.5	19.4	20.1	21.0	22.4
Other current assets, net	61.5	63.3	49.0	43.7	38.6	30.1	24.5	28.6
Income taxes	2.9			2.3	2.1	13.7	11.8	11.8
Deferred income taxes	28.1	14.0	19.3	18.7	19.9	10.7	18.6	19.2
Total Current Assets	662.6	687.0	677.2	661.4	660.4	567.8	511.6	554.4
Noncurrent Assets
Property, plant and equipment, net	365.8	351.8	356.3	357.2	366.5	369.3	369.6	372.4
Real estate held for entitlement and leasing	86.2	84.2	82.9	81.5	94.4	87.3	83.2	81.2
Recoverable from the U.S. government and other third parties for environmental remediation costs	210.4	123.2	76.8	79.3	87.2	89.6	87.5	92.5
Deferred income taxes	286.7	254.6	247.3	256.0	261.4	182.5	180.2	185.6
Goodwill	158.1	158.1	158.1	158.1	158.1	158.1	158.1	153.1
Intangible assets	108.8	112.1	115.5	118.8	122.2	125.6	128.9	132.3
Income taxes	7.9				6.6
Other noncurrent assets, net	85.7	116.6	115.5	99.8	93.0	94.1	86.9	80.0
Total Noncurrent Assets	1,372.3	1,270.6	1,222.1	1,234.3	1,258.2	1,174.5	1,161.6	1,163.4
Total Assets	2,034.9	1,957.6	1,899.3	1,895.7	1,918.6	1,742.3	1,673.2	1,717.8
Current Liabilities
Short-term borrowings and current portion of long-term debt	5.3	5.3	5.3	5.3	5.3	5.5	4.2	3.0
Accounts payable	105.2	88.7	88.1	85.0	104.0	115.4	94.4	97.1
Reserves for environmental remediation costs	32.6	37.6	38.7	38.3	31.9	35.0	36.0	38.0
Postretirement medical and life insurance benefits	6.0	6.4	6.4	6.4	6.4	7.2	7.2	7.2
Advance payments on contracts	203.7	211.7	197.3	207.0	197.4	116.0	103.4	94.2
Other current liabilities	201.3	243.7	200.9	213.5	221.4	218.1	183.7	217.7
Total Current Liabilities	554.1	593.4	536.7	555.5	566.4	497.2	428.9	457.2
Noncurrent Liabilities
Senior debt	88.8	90.0	91.3	92.5	93.8	95.0	96.3	41.9
Second-priority senior notes	460.0	460.0	460.0	460.0	460.0	460.0	460.0	460.0
Convertible subordinated notes	84.8	84.8	98.0	99.4	133.8	133.6	143.0	188.7
Other debt	13.1	21.1	63.3	81.3	89.3	89.4	79.5	0.5
Reserves for environmental remediation costs	273.5	198.5	122.8	124.3	134.1	133.6	127.7	132.4
Pension benefits	566.2	471.9	475.5	479.1	482.8	257.7	262.1	266.5
Postretirement medical and life insurance benefits	45.5	49.4	50.1	50.6	51.7	57.1	57.5	58.5
Other noncurrent liabilities	94.4	97.8	99.7	81.8	80.6	79.3	78.3	76.5
Total Noncurrent Liabilities	1,626.3	1,473.5	1,460.7	1,469.0	1,526.1	1,305.7	1,304.4	1,225.0
Total Liabilities	$ 2,180.4	2,066.9	1,997.4	2,024.5	$ 2,092.5	1,802.9	1,733.3	1,682.2
Commitments and contingencies
Redeemable common stock, par value of $0.10; 0.1 million shares issued and outstanding as of November 30, 2015 and 2014	$ 0.9	0.1	0.1	0.1	$ 1.6	0.2	0.1	0.1
Stockholders’ Deficit
Preference stock, par value of $1.00; 15.0 million shares authorized; none issued or outstanding	0.0				0.0
Common stock, par value of $0.10; 150.0 million shares authorized; 62.9 million shares issued and outstanding as of November 30, 2015; 56.9 million shares issued and outstanding as of November 30, 2014	6.5	6.4	6.3	6.3	5.9	5.9	5.9	5.9
Other capital	340.1	340.5	325.8	324.6	287.4	285.4	283.2	281.6
Treasury stock at cost, 3.5 million shares as of November 30, 2015 and 2014	(64.5)	(64.5)	(64.5)	(64.5)	(64.5)	(64.5)	(64.5)	(8.6)
Accumulated deficit	(86.8)	(94.5)	(56.6)	(73.9)	(70.6)	(82.5)	(72.0)	(22.8)
Accumulated other comprehensive loss, net of income taxes	(341.7)	(297.3)	(309.2)	(321.4)	(333.7)	(205.1)	(212.8)	(220.6)	(228.3)
Total Stockholders’ Deficit	(146.4)	(109.4)	(98.2)	(128.9)	(175.5)	(60.8)	(60.2)	35.5	$ 37.3	$ (394.3)
Total liabilities, redeemable common stock, and stockholders’ (deficit) equity	2,034.9	1,957.6	1,899.3	1,895.7	1,918.6	1,742.3	1,673.2	1,717.8
Northrop [Member]
Current Assets
Receivable from Northrop Grumman Corporation (“Northrop”)	6.0	6.0	6.0	6.0	6.0	6.0	6.0	6.0
Noncurrent Assets
Receivable from Northrop	$ 62.7	$ 70.0	$ 69.7	$ 69.4	$ 68.8	$ 68.0	$ 67.2	$ 66.3