Commitments And Contingencies (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Commitments And Contingencies [Line Items]
Expected revenue	$ 180.0
Maximum liability for damages	82.0
Performance bond issued	72.6
Surety Bond [Member]
Commitments And Contingencies [Line Items]
Values associated with surety arrangements	423.6
Additional bond amount	85.0
Amount exposed to bond	$ 234.4
Minimum [Member]
Commitments And Contingencies [Line Items]
Cost basis of component parts as a percentage of revenues	5.00%
Maximum liability for damages	$ 24.0
Estimated revenue decrease	$ 60.0
Maximum [Member]
Commitments And Contingencies [Line Items]
Cost basis of component parts as a percentage of revenues	10.00%
Maximum liability for damages	$ 34.0
Estimated revenue decrease	70.0
Utility-Scale Solar Project [Member]
Commitments And Contingencies [Line Items]
Surety bond issued	$ 205.0
Warranty period	3 years