Fair Value Measurement (Carrying Values And Fair Values Of The Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 3,097,350	$ 2,819,263
Long-term Debt, Fair Value	3,210,188	2,863,355
Term-A Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	736,500	1,245,175
Long-term Debt, Fair Value	747,188	1,254,855
4.75% Senior Notes Due 2025 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	784,334
Long-term Debt, Fair Value	810,000
5.00% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	983,510	981,949
Long-term Debt, Fair Value	1,035,000	1,002,500
4.75% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	593,006	592,139
Long-term Debt, Fair Value	$ 618,000	$ 606,000