Guarantees and Indemnifications (Details)	Sep. 30, 2015 USD ($)
Guarantee Of Financial Obligations Of Npt [Member]
Guarantee Obligations [Line Items]
Guarantee Obligations Maximum Exposure	$ 25,000,000
Various Subsidiary Surety Bonds And Performance Guarantees Expiring Between 2015 And 2016 [Member]
Guarantee Obligations [Line Items]
Guarantee Obligations Maximum Exposure	33,200,000
Guarantee Of Rocky River Reality And Nusco Lease Payments For Real Estate And Vehicles Expiring 2019 Through 2024 [Member]
Guarantee Obligations [Line Items]
Guarantee Obligations Maximum Exposure	12,200,000
Guarantee To Purchaser Of Es Boulos Company And A Bonding Company Expiring In 2016 And 2020 [Member]
Guarantee Obligations [Line Items]
Guarantee Obligations Maximum Exposure	38,200,000
Access Northeast Project Capital Contributions Guarantee Expiring In 2021 [Member]
Guarantee Obligations [Line Items]
Guarantee Obligations Maximum Exposure	$ 206.0