Fair Value Measurements and Derivative Instruments (Details) (Fair Value, Measurements, Nonrecurring, USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Total
Assets:
Cash and cash equivalents	$ 183,181	[1]	$ 204,687	[1]
Total Assets	183,181		204,687
Liabilities:
Long-term debt (including current portion of long-term debt)	7,241,824	[2]	8,431,220	[2]
Total Liabilities	7,241,824		8,431,220
Level 1
Assets:
Cash and cash equivalents	183,181	[1],[3]	204,687	[1],[3]
Total Assets	183,181	[3]	204,687	[3]
Liabilities:
Long-term debt (including current portion of long-term debt)	1,844,607	[2],[3]	2,888,255	[2],[3]
Total Liabilities	1,844,607	[3]	2,888,255	[3]
Level 2
Assets:
Cash and cash equivalents	0	[1]	0	[1]
Total Assets	0		0
Liabilities:
Long-term debt (including current portion of long-term debt)	5,397,217	[2]	5,542,965	[2]
Total Liabilities	5,397,217		5,542,965
Level 3
Assets:
Cash and cash equivalents	0	[1]	0	[1]
Total Assets	0		0
Liabilities:
Long-term debt (including current portion of long-term debt)	0	[2]	0	[2]
Total Liabilities	0		0
Reported Value Measurement
Assets:
Cash and cash equivalents	183,181	[1]	204,687	[1]
Total Assets	183,181		204,687
Liabilities:
Long-term debt (including current portion of long-term debt)	6,931,171	[2]	8,020,061	[2]
Total Liabilities	$ 6,931,171		$ 8,020,061

[1] Consists of cash and marketable securities with original maturities of less than 90 days.

[2] Consists of unsecured revolving credit facilities, unsecured senior notes, senior debentures and unsecured term loans. Does not include our capital lease obligations.

[3] Inputs based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access. Valuation of these items does not entail a significant amount of judgment.