Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, aggregate fair value		$ 2,107,000	$ 2,104,000
Long-term debt, aggregate carrying amount, net of unamortized discounts		2,048,813	2,082,368
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	104	85
Recurring Basis [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps		8,067	8,334
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	104	85
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Basis [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps		0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Basis [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps		8,067	8,334
Significant Unobservable Inputs (Level 3) [Member] | Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	0	0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Basis [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps		$ 0	$ 0

[1] (a) Available-for-sale securities are included in Other assets, net in the accompanying Condensed Consolidated Balance Sheets.