Fair Value Disclosures (Estimated Fair Values and Carrying Amounts of Assets and Liabilities) (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	$ 199,663,000	$ 567,599,000
Cash and cash equivalents, fair value	199,663,000	567,599,000
Restricted cash, current and non-current, carrying value	122,913,000	129,547,000
Restricted cash, current and non-current, fair value	122,913,000	129,547,000
Long-term debt and other obligations, carrying amount	13,841,265,000	12,171,142,000
Long-term debt and other obligations, fair value	14,399,704,000	$ 12,660,013,000
Cash and Cash Equivalents [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	1
Restricted cash, current and non-current, carrying value	1
Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt and other obligations, carrying amount	$ 2