Business Acquisitions (Details) (USD $)	3 Months Ended								12 Months Ended			9 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2010 Spacecraft Business [Member]	Dec. 31, 2011 Spacecraft Business [Member]	Apr. 02, 2010 Spacecraft Business [Member]
Business Acquisition [Line Items]
Amount of cash paid to acquire certain assets and liabilities														$ 55,000,000
Revenues	335,451,000	342,170,000	350,599,000	317,703,000	346,142,000	314,519,000	337,726,000	296,190,000	1,345,923,000	1,294,577,000	1,125,295,000	69,800,000
Operating income	22,203,000	24,668,000	22,807,000	10,116,000	24,065,000	19,356,000	12,228,000	17,365,000	79,794,000	73,014,000	52,293,000	7,300,000
Purchase price allocation [Abstract]
Property plant and equipment													42,268,000
Intangible assets													7,100,000
Goodwill													19,710,000
Net working capital													(14,078,000)
Total purchase price													55,000,000
Goodwill purchase accounting adjustments [Abstract]
Goodwill purchase accounting adjustments									$ 514,000