Summary of Significant Accounting Policies - Divestitures (Details) - Assets Disposed of by Sale - USD ($) $ in Millions			12 Months Ended
	Mar. 25, 2016	Jan. 22, 2016	Dec. 31, 2016
Electronic Systems | Pittsburgh, Pennsylvania Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received		$ 38.5
Assets divested, net		24.0
Liabilities divested, net		4.0
Transaction costs		0.2
Gain (loss) on divestiture		$ 18.3
Electronic Systems | Miltec Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	$ 14.6
Assets divested, net	15.4
Liabilities divested, net	2.6
Transaction costs	1.3
Gain (loss) on divestiture	$ 0.5
Ducommun La Barge Technologies | Pittsburgh, Pennsylvania Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received			$ 38.6
Assets divested, net			24.0
Liabilities divested, net			4.0
Transaction costs			0.3
Gain (loss) on divestiture			18.3
Ducommun La Barge Technologies | Miltec Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received			13.3
Assets divested, net			15.4
Liabilities divested, net			2.7
Transaction costs			1.3
Gain (loss) on divestiture			$ (0.7)