Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($) pension_plan	Dec. 31, 2014 USD ($)	Dec. 31, 2013
Summary of Significant Accounting Policies [Line Items]
Equity investments, unamortized excess net investment		$ 76.7	$ 79.0
Intangible asset estimated useful life		6 years
Interest capitalization threshold for construction in process		$ 0.5
Long-term Debt, Weighted Average Interest Rate	[1]	4.70%	4.90%	5.20%
Number of Pension Plans | pension_plan		3
Deferred Cost Multiplier		0.5
Board of Director Deferred Award Days to Payment		60 days
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Intangible asset estimated useful life		5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Intangible asset estimated useful life		25 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Performance Shares [Member]
Summary of Significant Accounting Policies [Line Items]
Equity-based compensation, award payout percentage, minimum		0.00%
Equity-based compensation, award payout percentage, maximum		200.00%
Equity Based Compensation Award Payout Fluctuation Of Award Market		50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years

[1] Weighted-average interest rate includes the amortization/accretion of discounts, premiums and gains/losses realized on historical cash flow and fair value hedges recognized as interest expense.