Quarterly report pursuant to Section 13 or 15(d)

Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details)

v3.8.0.1
Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2018
Jun. 30, 2018
Dec. 31, 2017
VA&E [Member]      
Schedule Of Equity Method Investments [Line Items]      
Line of Credit Facility, Maximum Borrowing Capacity $ 3.5    
Outstanding Working Capital Advances At End Of Period 3.6    
Proceeds from Unsecured Lines of Credit 0.9    
Payments for Advance to Affiliate (4.4)    
Other Corporate Joint Ventures [Member]      
Schedule Of Equity Method Investments [Line Items]      
Outstanding Working Capital Advances At End Of Period 2.0    
Proceeds from Collection of Advance to Affiliate     $ (0.4)
Subordinated Debt [Member] | VA&E [Member]      
Schedule Of Equity Method Investments [Line Items]      
Outstanding Working Capital Advances At End Of Period $ 3.5    
Subsequent Event [Member]      
Schedule Of Equity Method Investments [Line Items]      
Proceeds from Equity Method Investment, Distribution, Return of Capital   $ 70.0