Contingencies (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012 flare	Mar. 31, 2013 flare	Mar. 31, 2012 flare
Loss Contingency [Abstract]
Additional warranty accrual	$ 7,800,000		$ 10,700,000
Maximum number of flares	76,000	76,000	76,000
Unbilled receivables for contract claims		27,797,000
Environmental liabilities discount rate, net of estimated inflation (as a percent)		0.80%	1.00%
Environmental receivable discount rate, net of estimated inflation (as a percent)		0.80%	1.00%
Treasury constant maturities rate used to estimate discount rate (in years)		20 years
Estimated inflationary factor (as a percent)		1.90%
Rounding precision of estimated inflationary factor (as a percent)		0.25%
Environmental remediation
Amounts (payable) receivable		(58,965,000)	(61,227,000)
Unamortized discount		2,745,000	3,731,000
Amounts (payable) receivable		34,190,000	35,638,000
Unamortized discount		(1,446,000)	(1,925,000)
Accrual for Environmental Loss Contingencies, Net		(56,220,000)	(57,496,000)
Accrual for Environmental Loss Contingencies Net of Recoveries		32,744,000	33,713,000
Discounted liability recorded in other current liabilities		6,847,000	5,135,000
Discounted liability recorded in other long-term liabilities		49,373,000	52,361,000
Discounted receivable recorded in other current assets		4,490,000
Discounted receivable recorded in other non-current assets		28,254,000
Threshold for Hercules to indemnify the Company for environmental remediation		50,000,000
Aggregate undiscounted amounts payable for environmental remediation costs, net of expected recoveries
Fiscal 2014		2,357,000
Fiscal 2015		299,000
Fiscal 2016		304,000
Fiscal 2017		2,543,000
Fiscal 2018		2,063,000
Thereafter		17,209,000
Total		24,775,000
Minimum
Acquisitions
Period beyond balance sheet date for classifying the environmental remediation as non-current (in years)		1 year
Estimated discounted reasonably possible costs of environmental remediation		56,220,000
Maximum
Acquisitions
Estimated discounted reasonably possible costs of environmental remediation		83,245,000
Thiokol | Environmental Remediation Cost Sharing Level 1 | Maximum
Acquisitions
Threshold for environmental remediation if costs are not recovered through U.S. Government contracts		29,000,000
Thiokol | Environmental Remediation Cost Sharing Level 2 | Minimum
Acquisitions
Threshold for environmental remediation if costs are not recovered through U.S. Government contracts		29,000,000
Thiokol | Environmental Remediation Cost Sharing Level 2 | Maximum
Acquisitions
Threshold for environmental remediation if costs are not recovered through U.S. Government contracts		49,000,000
Thiokol | Environmental Remediation Cost Sharing Level 3 | Minimum
Acquisitions
Threshold for environmental remediation if costs are not recovered through U.S. Government contracts		$ 49,000,000