Balance Sheet Accounts and Supplemental Disclosures - Narrative - Assets Held for Sale (Details)		1 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended			13 Months Ended
	Feb. 28, 2015 a	Dec. 31, 2015 USD ($)	Jul. 31, 2015 USD ($)	May 31, 2015 USD ($) a	May 31, 2015 USD ($) a	Dec. 31, 2016 USD ($) a	Nov. 30, 2015 USD ($)	Nov. 30, 2014 USD ($)	Dec. 31, 2015 USD ($)
Long Lived Assets Held-for-sale [Line Items]
Acres of land | a	5,563
Proceeds from sale of intellectual property		$ 0				$ 500,000	$ 1,000,000	$ 7,500,000
Aerospace and Defense | Energy Business [Member]
Long Lived Assets Held-for-sale [Line Items]
Expenses incurred to divest			$ 1,800,000
Net sales							600,000	600,000
Discontinued Operations, Disposed of by Sale [Member]
Long Lived Assets Held-for-sale [Line Items]
Proceeds from sale of intellectual property								7,500,000
Discontinued Operations, Disposed of by Sale [Member] | Other, net [Member]
Long Lived Assets Held-for-sale [Line Items]
Gain on sale								$ 6,800,000
Developable Portions Of Holdback Acreage [Member] | Discontinued Operations, Disposed of by Sale [Member]
Long Lived Assets Held-for-sale [Line Items]
Acres of land | a						150
Total purchase price						$ 6,700,000
Area 40 | Discontinued Operations, Disposed of by Sale [Member]
Long Lived Assets Held-for-sale [Line Items]
Acres of land | a						50
Hillsborough
Long Lived Assets Held-for-sale [Line Items]
Income from continuing operations before income taxes from land sale							$ 30,600,000		$ 30,600,000
Hillsborough | Discontinued Operations, Disposed of by Sale [Member]
Long Lived Assets Held-for-sale [Line Items]
Acres of land | a				550	700
Total purchase price				$ 57,000,000	$ 57,000,000
Cash proceeds from sale of land				46,700,000
Cash received at initial closing				40,000,000
Income from continuing operations before income taxes from land sale				30,600,000
Hillsborough | Discontinued Operations, Disposed of by Sale [Member] | Notes Receivable [Member]
Long Lived Assets Held-for-sale [Line Items]
Promissory note				10,300,000	10,300,000
Hillsborough | Discontinued Operations, Disposed of by Sale [Member] | Interest Bearing Notes Receivable [Member]
Long Lived Assets Held-for-sale [Line Items]
Promissory note				$ 9,000,000.0	$ 9,000,000.0
Hillsborough
Long Lived Assets Held-for-sale [Line Items]
Acres of land | a	550