Stockholders' Equity (Tables)

12 Months Ended

Mar. 31, 2013

Equity [Abstract]

Weighted average assumptions used in estimating the value of the award

The weighted average assumptions used in estimating the value of the TSR award were as follows:

	Fiscal 2012		Fiscal 2011
Risk-free rate	1.22	%	1.35	%
Expected volatility	27.90	%	27.7	%
Expected dividend yield	1.17	%	0.7	%
Expected award life	3		3

The following weighted average assumptions were used for grants:

	Year ended March 31, 2013	Year ended March 31, 2012
Risk-free rate	1.02%-1.22%	0.82%
Expected volatility	25.87%	25.03%
Expected dividend yield	1.49%-1.90%	1.27%
Expected option life	7 years	7 years

Schedule of stock option activity

A summary of ATK's stock option activity is as follows:

	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (per option)
Outstanding at March 31, 2010	865,373		$	60.56
Granted	—		—
Exercised	(251,406	)	54.97
Forfeited/expired	(7,045	)	62.32
Outstanding at March 31, 2011	606,922		62.85		1.2	$	11.29
Granted	135,661		56.79
Exercised	(107,944	)	52.88
Forfeited/expired	(216,517	)	65.64
Outstanding at March 31, 2012	418,122		62.02		2.7	—
Granted	114,628		65.32
Exercised	(93,617	)	58.34
Forfeited/expired	(176,885	)	66.55
Outstanding at March 31, 2013	262,248		$	61.72	8.4	$	11.47
Options exercisable at:
March 31, 2013	70,145		$	61.28	5.2	$	13.98
March 31, 2012	282,461		$	64.53	0.7	$	—
March 31, 2011	601,922		$	62.50	1.2	$	11.38

Schedule of performance share award, TSR award, and restricted stock award activity

A summary of ATK's performance share award, TSR award, and restricted stock award activity is as follows:

	Shares		Weighted Average Grant Date Fair Value
Nonvested at March 31, 2010	353,480		$	80.71
Granted	723,759		70.43
Canceled/forfeited	(94,599	)	84.30
Vested	(128,116	)	96.30
Nonvested at March 31, 2011	854,524		78.85
Granted	347,287		60.63
Canceled/forfeited	(161,307	)	61.79
Vested	(64,263	)	69.51
Nonvested at March 31, 2012	976,241		67.08
Granted	213,536		63.17
Canceled/forfeited	(287,326	)	69.44
Vested	(144,009	)	68.59
Nonvested at March 31, 2013	758,442		$	65.42