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Summary of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 reporting_unit technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of reporting units for purposes of testing goodwill for impairment \| reporting_unit	3
Minimum time required for an award not to be subject to forfeiture, in months	6 months
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Length of construction period for interest capitalization, in years	1 year
Minimum \| Net properties, plants and equipment
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of methods used to determine fair value \| technique	1