CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Costs and estimated earnings on long-term contracts, progress billings	$ 47,357	$ 64,099
Property, plant and equipment, net of accumulated depreciation	109,693	99,650
Intangible assets, net of accumulated amortization	82,889	73,879
Advance payments on long-term contracts, costs incurred	$ 55,485	$ 59,772
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	30,468,824	30,468,824
Treasury stock, shares	4,623,958	4,635,622