Stock Plans and Equity Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum expiration term following grant date (in years)	10Y
Stock-based compensation, additional disclosures [Abstract]
Stock-based compensation expense recognized	$ 6,200,000		$ 7,000,000		$ 9,200,000
Income tax benefit related to stock-based compensation expense	2,000,000		2,300,000		3,100,000
Intrinsic value of options exercised, computed as the market price on the exercise date less the price paid to exercise the options	3,800,000		8,100,000		600,000
Cash received from exercise of options	1,400,000		10,600,000		1,100,000
Grant date fair value of vested restricted stock units	6,100,000		7,000,000		10,100,000
Tax benefit (expense) recorded as an increase (decrease) to additional paid-in capital related to stock-based compensation transactions	1,235,000		1,078,000		(1,007,000)
Shares of common stock available for grant under the company's stock-based incentive plans (in shares)	945,000
Aggregate intrinsic value of restricted stock units that are expected to vest	11,400,000
Unrecognized compensation expense related to non-vested restricted stock units	10,100,000
Unrecognized compensation expense, weighted-average period of recognition (in years)	2.17
Aggregate intrinsic value of stock options outstanding, all fully vested	6,600,000
Securities Repurchase Transactions [Abstract]
Repurchases of common stock (in shares)					(1,169,000)
Cost of common stock repurchased and retired					(16,681,000)
Range 1 of Exercise Prices [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	$ 4.33
Upper range limit (in dollars per share)	$ 7.08
Number Outstanding (in shares)	545,711	[1]
Weighted Average Remaining Contractual Term (Years)	1.29
Weighted Average Exercise Price (in dollars per share)	$ 5.89
Range 2 of Exercise Prices [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	$ 7.09
Upper range limit (in dollars per share)	$ 12.18
Number Outstanding (in shares)	306,576	[1]
Weighted Average Remaining Contractual Term (Years)	1.77
Weighted Average Exercise Price (in dollars per share)	$ 8.73
Range 3 of Exercise Prices [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	$ 12.19
Upper range limit (in dollars per share)	$ 12.98
Number Outstanding (in shares)	50,000	[1]
Weighted Average Remaining Contractual Term (Years)	4.01
Weighted Average Exercise Price (in dollars per share)	$ 12.98
Stock Options [Member]
Summary of Stock Option Activity [Roll Forward]
Outstanding at beginning of period (in shares)	1,226,582		2,301,305		2,500,233
Exercised (in shares)	(317,647)		(1,038,624)		(107,728)
Forfeited (in shares)	(448)		(2,599)		(7,500)
Expired (in shares)	(6,200)		(33,500)		(83,700)
Outstanding at end of period (in shares)	902,287	[2]	1,226,582		2,301,305
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 6.46		$ 8.29		$ 9.01
Exercised (in dollars per share)	$ 4.26		$ 10.21		$ 9.82
Forfeited (in dollars per share)	$ 5.79		$ 6.29		$ 12.15
Expired (in dollars per share)	$ 3.91		$ 16.24		$ 27.52
Outstanding at end of period (in dollars per share)	$ 7.25		$ 6.46		$ 8.29
Weighted average remaining contractual term (in years)	1.60
Restricted Stock Units [Member]
Summary of Restricted Stock Units Activity [Roll Forward]
Outstanding at beginning of period (in shares)	684,674		473,615		877,794
Granted (in shares)	442,110	[3]	520,470	[3]	86,760	[3]
Vested (in shares)	(330,356)		(300,969)		(466,155)
Forfeited (in shares)	(14,316)		(8,442)		(24,784)
Outstanding at end of period (in shares)	782,112		684,674		473,615
Weighted Average Measurement Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 16.38		$ 22.88		$ 23.01
Granted (in dollars per share)	$ 17.39		$ 14.47		$ 15.14
Vested (in dollars per share)	$ 18.47		$ 23.17		$ 21.69
Forfeited (in dollars per share)	$ 16.57		$ 19.98		$ 23.18
Outstanding at end of period (in dollars per share)	$ 16.07		$ 16.38		$ 22.88
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount from market price (in hundredths)	85.00%
Shares of common stock available for purchase (in shares)	540,000
Stock-based compensation, additional disclosures [Abstract]
Stock-based compensation expense recognized	$ 400,000		$ 400,000		$ 400,000

[1] All outstanding options were exercisable as of December 31, 2011.

[2] The weighted average remaining contractual term is 1.60 years.

[3] The fair value of restricted stock unit grants is determined based on the closing market price of Orbital's common stock on the date of grant. Such value is recognized as expense over the service period, net of estimated forfeitures.