Fair Value Disclosures (Estimated Fair Values and Carrying Amounts of Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	$ 37,850	$ 26,231	$ 39,945	$ 31,036
Debt and other obligations, carrying amount	1,500,000	1,500,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	37,850	26,231
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt and other obligations, fair value	$ 1,498,050	$ 1,497,750