Debt (Schedule of Long-Term Debt) (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2009
Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	2.15%
Debt instrument maturity year, start	2019
Debt instrument maturity year, end	2026
Senior notes, 7.50%, due 2019 [Member]
Debt Instrument [Line Items]
Interest Rate	7.50%	7.50%	7.50%
Debt instrument maturity year	2019
Revenue bonds, 2.75% due 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	2.75%	2.75%
Debt instrument maturity year	2024
Medium-term notes, 8.75% to 8.89%, due 2017 through 2022 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year, start	2017
Debt instrument maturity year, end	2022
Minimum [Member] | Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	2.50%	2.50%
Minimum [Member] | Medium-term notes, 8.75% to 8.89%, due 2017 through 2022 [Member]
Debt Instrument [Line Items]
Interest Rate	8.75%	8.75%
Maximum [Member] | Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	3.00%	3.00%
Maximum [Member] | Medium-term notes, 8.75% to 8.89%, due 2017 through 2022 [Member]
Debt Instrument [Line Items]
Interest Rate	8.89%	8.89%
Debt Instrument, Redemption, Period One [Member] | Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year, start	2017
Debt instrument maturity year, end	2024
Debt Instrument, Redemption, Period One [Member] | Minimum [Member] | Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	2.95%	2.95%
Debt Instrument, Redemption, Period One [Member] | Maximum [Member] | Term loans, variable rate 2.50% to 3.00% due 2019 through 2026 and fixed rate 2.95% to 4.64% due 2017 through 2024 [Member]
Debt Instrument [Line Items]
Interest Rate	4.64%	4.64%