Fair Value Measurements (Quantitative Information About Significant Unobservable Inputs (Level 3) Used) (Details) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Discounted Cash Flows [Member] | Fixed-Rate Debt [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Discount Rate		2.10%	1.30%
Discounted Cash Flows [Member] | Fixed-Rate Debt [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Discount Rate		5.30%	5.10%
Discounted Cash Flows [Member] | Variable-Rate Debt [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Discount Rate		1.20%	1.20%
Discounted Cash Flows [Member] | Variable-Rate Debt [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Discount Rate		2.90%	2.90%
Discounted Cash Flows [Member] | Tax Increment Revenue Bonds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Discount Rate		7.50%	7.50%
Discounted Cash Flows [Member] | Tax Increment Revenue Bonds [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Expected Future Growth Rate		1.00%	1.00%
Fair Value Input, Expected Future Inflation Rate		1.00%	1.00%
Discounted Cash Flows [Member] | Tax Increment Revenue Bonds [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input, Expected Future Growth Rate		5.00%	2.00%
Fair Value Input, Expected Future Inflation Rate		2.00%	2.00%
Fair Value [Member] | Fixed-Rate Debt [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt		$ 1,936,881	$ 1,719,775
Fair Value [Member] | Variable-Rate Debt [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt		221,647	292,972
Fair Value [Member] | Tax Increment Revenue Bonds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments	[1]	$ 25,377	$ 25,392

[1] At September 30, 2015 and December 31, 2014, the credit loss balance on our tax increment revenue bonds was $31.0 million.